# Bootstrap Multiselect

If you are interested in actively maintaining this project, please contact me (see GitHub profile for contact information).

Please consult the FAQ, the Issue Tracker or StackOverflow before creating a new issue; when creating an issue or a pull request, read how to contribute first.

Consider making a donation to support the development of this plugin:

Why Donate?

## Getting Started

1. ### Link the Required Files

   First, the jQuery library needs to be included. Then Twitter Bootstrap - both the Javascript library and the CSS stylesheet - needs to be included.

       <!-- Include Twitter Bootstrap and jQuery: -->
       <link rel="stylesheet" href="css/bootstrap.min.css" type="text/css"/>
       <script type="text/javascript" src="js/jquery.min.js"></script>
       <script type="text/javascript" src="js/bootstrap.min.js"></script>

       <!-- Include the plugin's CSS and JS: -->
       <script type="text/javascript" src="js/bootstrap-multiselect.js"></script>
       <link rel="stylesheet" href="css/bootstrap-multiselect.css" type="text/css"/>

   The jQuery library can also be included using a CDN, for example the Google CDN:

       <script src="//ajax.googleapis.com/ajax/libs/jquery/2.0.3/jquery.min.js"></script>

   Note that the plugin will work both with version 2.x of the jQuery library as well as with version 1.10.x of the jQuery library. So for using the Google CDN you may have to adjust the version.

2. ### Create a Select

   Now simply use HTML to create your `select` input which you want to turn into a multiselect. Remember to set the `multiple` attribute as to get a real multiselect - but do not worry, the plugin can also be used as usual select without the `multiple` attribute being present.

       <!-- Build your select: -->
       <select id="example-getting-started" multiple="multiple">
           <option value="cheese">Cheese</option>
           <option value="tomatoes">Tomatoes</option>
           <option value="mozarella">Mozzarella</option>
           <option value="mushrooms">Mushrooms</option>
           <option value="pepperoni">Pepperoni</option>
           <option value="onions">Onions</option>
       </select>

3. ### Call the Plugin

   In the end, simply call the plugin on your `select`. You may also specify further options, see the Options tab for further information.

       <!-- Initialize the plugin: -->
       <script type="text/javascript">
           $(document).ready(function() {
               $('#example-getting-started').multiselect();
           });
       </script>

## Configuration Options

Overview
`multiple` | `enableHTML` | `enableClickableOptGroups`
`enableCollapsibleOptGroups` | `collapseOptGroupsByDefault` | `disableIfEmpty`
| `dropRight` | `dropUp` | `maxHeight`
`disableIfEmpty` | `disabledText` | `onChange`
`onInitialized` | `onDropdownShow` | `onDropdownHide`
`onDropdownShown` | `onDropdownHidden` | `buttonClass`
`inheritClass` | `buttonContainer` | `buttonWidth`
`buttonText` | `buttonTitle` | `nonSelectedText`
`nSelectedText` | `allSelectedText` | `numberDisplayed`
`delimiterText` | `optionLabel` | `optionClass`
`selectedClass` | `includeSelectAllOption` | `selectAllJustVisible`
`selectAllText` | `selectAllValue` | `selectAllName`
`selectAllNumber` | `onSelectAll` | `onDeselectAll`
`enableFiltering` | `enableCaseInsensitiveFiltering` | `enableFullValueFiltering`
`filterBehavior` | `filterPlaceholder` | `includeResetOption`
`includeResetDivider` | `resetText`

Use Firebug, Chrome Developer Tools to get the best out of the below examples.

`multiple` | `multiple` is not a real configuration option. It refers to the `multiple` attribute of the `select` the plugin is applied on. When the `multiple` attribute of the `select` is present, the plugin uses checkboxes to allow multiple selections. If it is not present, the plugin uses radio buttons to allow single selections. When using the plugin for single selections (without the `multiple` attribute present), the first option will automatically be selected if no other option is selected in advance. See #129 for how to avoid this behavior. The following example shows the default behavior when the `multiple` attribute is omitted:
    <script type="text/javascript">
        $('#example-single').multiselect();
    </script>
    <!-- Note the missing multiple attribute! -->
    <select id="example-single">
        <option value="1">Option 1</option>
        <option value="2">Option 2</option>
        <option value="3">Option 3</option>
        <option value="4">Option 4</option>
        <option value="5">Option 5</option>
        <option value="6">Option 6</option>
    </select>
If multiple options are selected in advance and the `select` lacks the `multiple` attribute, the last option marked as `selected` will initially be selected by the plugin.
    <script type="text/javascript">
        $('#example-single-selected').multiselect();
    </script>
    <!-- Note the missing multiple attribute! -->
    <select id="example-single-selected">
        <option value="1">Option 1</option>
        <option value="2" selected="selected">Option 2</option>
        <!-- Option 3 will be selected in advance ... -->
        <option value="3" selected="selected">Option 3</option>
        <option value="4">Option 4</option>
        <option value="5">Option 5</option>
        <option value="6">Option 6</option>
    </select>
The following example shows the default behavior when the `multiple` attribute is present. Initially selected options will be adopted automatically:
    <script type="text/javascript">
        $('#example-multiple-selected').multiselect();
    </script>
    <!-- Note the missing multiple attribute! -->
    <select id="example-multiple-selected" multiple="multiple">
        <option value="1">Option 1</option>
        <option value="2" selected="selected">Option 2</option>
        <!-- Option 3 will be selected in advance ... -->
        <option value="3" selected="selected">Option 3</option>
        <option value="4">Option 4</option>
        <option value="5">Option 5</option>
        <option value="6">Option 6</option>
    </select>
The plugin naturally supports `optgroup`s, however the group headers are not clickable by default. See the `enableClickableOptGroups` option for details.
    <script type="text/javascript">
        $('#example-multiple-optgroups').multiselect();
    </script>
    <select id="example-multiple-optgroups">
        <optgroup label="Group 1">
            <option value="1-1">Option 1.1</option>
            <option value="1-2" selected="selected">Option 1.2</option>
            <option value="1-3" selected="selected">Option 1.3</option>
        </optgroup>
        <optgroup label="Group 2">
            <option value="2-1">Option 2.1</option>
            <option value="2-2">Option 2.2</option>
            <option value="2-3">Option 2.3</option>
        </optgroup>
    </select>
Note that the classes of the `optgroup`s are adopted, allowing to select individual `optgroup`s easily (inspect the created markup to note the difference!):
    <script type="text/javascript">
        $('#example-multiple-optgroups-classes').multiselect();
    </script>
    <select id="example-multiple-optgroups">
        <optgroup label="Group 1" class="group-1">
            <option value="1-1">Option 1.1</option>
            <option value="1-2" selected="selected">Option 1.2</option>
            <option value="1-3" selected="selected">Option 1.3</option>
        </optgroup>
        <optgroup label="Group 2" class="group-2">
            <option value="2-1">Option 2.1</option>
            <option value="2-2">Option 2.2</option>
            <option value="2-3">Option 2.3</option>
        </optgroup>
    </select>
`enableHTML` | XSS injection is a serious threat for all modern web applications. Setting `enableHTML` to `false` (default setting) will create a XSS safe multiselect.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-xss').multiselect();
        });
    </script>
    <select id="example-xss" multiple="multiple">
        <option value="1">&lt;script&gt;alert(1);&lt;/script&gt;</option>
    </select>
On the other hand, when setting `enableHTML` to `true`, the plugin will support HTML within `option`s:
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-xss-html').multiselect();
        });
    </script>
    <select id="example-xss-html" multiple="multiple">
        <option value="1">&gt;span style="color:red"&lt;Option 1&gt;/span&gt;</option>
    </select>
`enableClickableOptGroups` | If set to `true`, `optgroup`'s will be clickable, allowing to easily select multiple options belonging to the same group. `enableClickableOptGroups` is not available in single selection mode, i.e. when the `multiple` attribute is not present. When using `selectedClass`, the selected classes are also applied on the option groups.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-enableClickableOptGroups').multiselect({
                enableClickableOptGroups: true
            });
        });
    </script>
Note that this option does also work with disabled options:
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-enableClickableOptGroups-disabled').multiselect({
                enableClickableOptGroups: true
            });
        });
    </script>
Note that the behavior of `onChange` changes. Whenever an optgroup is changed/clicked, the `onChange` event is fired with all affected options as first parameter.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-enableClickableOptGroups-onChange').multiselect({
                enableClickableOptGroups: true,
                onChange: function(option, checked) {
                    alert(option.length + ' options ' + (checked ? 'selected' : 'deselected'));
                }
            });
        });
    </script>
Note that the `optgroup`'s are automatically selected if a whole group is selected by default:
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-enableClickableOptGroups-init').multiselect({
                enableClickableOptGroups: true
            });
        });
    </script>
`enableCollapsibleOptGroups` | If set to `true`, `optgroup`'s will be collapsible.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-enableCollapsibleOptGroups').multiselect({
                enableCollapsibleOptGroups: true
            });
        });
    </script>
Both options, `enableCollapsibleOptGroups` and `enableClickableOptGroups`, can also be combined: Note, however, that the behavior of combining both options might not be as expected - play around with the below example to get some intuition.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-enableCollapsibleOptGroups-enableClickableOptGroups').multiselect({
                enableClickableOptGroups: true,
                enableCollapsibleOptGroups: true
            });
        });
    </script>
The groups can be collapsed by default using the following simple trick:
    <script type="text/javascript">
    $(document).ready(function() {
        $('#example-enableCollapsibleOptGroups-collapsed').multiselect({
            enableCollapsibleOptGroups: true,
            buttonContainer: '<div id="example-enableCollapsibleOptGroups-collapsed-container" class="btn-group" />'
        });
        $('#example-enableCollapsibleOptGroups-collapsed-container .caret-container').click();
    });
    </script>
Combining the above with `enableFiltering` and `includeSelectAllOption`: Again, note, that the behavior of combining `enableCollapsibleOptGroups`, `enableCollapsibleOptGroups`, `enableFiltering` and `includeSelectAllOption` is not thoroughly tested. Experiment with the example below to get some intuition.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-enableCollapsibleOptGroups-enableClickableOptGroups-enableFiltering-includeSelectAllOption').multiselect({
                enableClickableOptGroups: true,
                enableCollapsibleOptGroups: true,
                enableFiltering: true,
                includeSelectAllOption: true
            });
        });
    </script>
`collapseOptGroupsByDefault` | This option will collapse all `optgroup`s by default. There is also an example in the Further Examples section demonstrating an alternative way of collapsing `optgroups` by default.
        <script type="text/javascript">
            $(document).ready(function() {
                $('#example-collapseOptGroupsByDefault').multiselect({
                    enableCollapsibleOptGroups: true,
                    collapseOptGroupsByDefault: true
                });
            });
        </script>
`disableIfEmpty` | If set to `true`, the multiselect will be disabled if no options are given.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-disableIfEmpty').multiselect({
                disableIfEmpty: true
            });
        });
    </script>
`disabledText` | The text shown if the multiselect is disabled. Note that this option is set to the empty string `''` by default, that is `nonSelectedText` is shown if the multiselect is disabled and no options are selected.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-disabledText').multiselect({
                disableIfEmpty: true,
                disabledText: 'Disabled ...'
            });
        });
    </script>
The `disabledText` option does also work when the underlying `select` is disabled:
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-disabledText-disabled').multiselect({
                disabledText: 'Disabled ...'
            });
        });
    </script>
    <select id="example-disabledText-disabled" multiple="multiple" disabled="disabled">
        <option value="1">Option 1</option>
        <option value="2">Option 2</option>
        <option value="3">Option 3</option>
        <option value="4">Option 4</option>
        <option value="5">Option 5</option>
        <option value="6">Option 6</option>
    </select>
Note that selected options will still be shown:
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-disabledText-disabled-selected').multiselect({
                disabledText: 'Disabled ...'
            });
        });
    </script>
    <select id="example-disabledText-disabled-selected" multiple="multiple" disabled="disabled">
        <option value="1">Option 1</option>
        <option value="2" selected="selected">Option 2</option>
        <option value="3" selected="selected">Option 3</option>
        <option value="4">Option 4</option>
        <option value="5">Option 5</option>
        <option value="6">Option 6</option>
    </select>
`dropRight` | The dropdown can also be dropped right.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-dropRight').multiselect({
                buttonWidth: '400px',
                dropRight: true
            });
        });
    </script>
`dropUp` | The dropdown can also be dropped up. Note that it is recommended to also set `maxHeight`. The plugin calculates the necessary height of the dropdown and takes the minimum of the calculated value and `maxHeight`. Note that this feature has been introduced in #594 and is known to have issues depending on the environment. An example of automatically adding the `dropUp` option when scrolling can be found in Further Examples.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-dropUp').multiselect({
                enableFiltering: true,
                includeSelectAllOption: true,
                maxHeight: 400,
                dropUp: true
            });
        });
    </script>
    <select id="example-dropUp" multiple="multiple">
        <option value="1">Option 1</option>
        <option value="2">Option 2</option>
        <option value="3">Option 3</option>
        <option data-role="divider"></option>
        <option value="4">Option 4</option>
        <option value="5">Option 5</option>
        <option value="6">Option 6</option>
    </select>
`maxHeight` | The maximum height of the dropdown. This is useful when using the plugin with plenty of options. The multiselect on the left uses `maxHeight` set to `200`. On the other hand, the multiselect on the right does not use `maxHeight`.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-with-maxHeight').multiselect({
                maxHeight: 200
            });
        });
    </script>
`checkboxName` | The name used for the generated checkboxes. See Server-Side Processing for details.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-checkboxName').multiselect({
                checkboxName: function(option) {
                    return 'multiselect[]';
                }
            });
        });
    </script>
`onChange` | A function which is triggered on the change event of the options. Note that the event is not triggered when selecting or deselecting options using the `select` and `deselect` methods provided by the plugin. Note that the behavior of `onChange` changes when setting `enableClickableOptGroups` to `true`.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-onChange').multiselect({
                onChange: function(option, checked, select) {
                    alert('Changed option ' + $(option).val() + '.');
                }
            });
        });
    </script>
`onInitialized` | A function which is triggered when the multiselect is finished initializing.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-onInitialized-button').on('click', function() {
                $('#example-onInitialized').multiselect({
                    onInitialized: function(select, container) {
                        alert('Initialized.');
                    }
                });
            });
        });
    </script>
    <div class="btn-group">
        <select id="example-onInitialized" multiple="multiple">
            <option value="1">Option 1</option>
            <option value="2">Option 2</option>
            <option value="3">Option 3</option>
            <option value="4">Option 4</option>
            <option value="5">Option 5</option>
            <option value="6">Option 6</option>
        </select>
        <button id="example-onInitialized-button" class="btn btn-primary">Activate!</button>
    </div>
`onDropdownShow` | A callback called when the dropdown is shown. The `onDropdownShow` option is not available when using Twitter Bootstrap 2.3.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-onDropdownShow').multiselect({
                onDropdownShow: function(event) {
                    alert('Dropdown shown.');
                }
            });
        });
    </script>
`onDropdownHide` | A callback called when the dropdown is closed. The `onDropdownHide` option is not available when using Twitter Bootstrap 2.3.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-onDropdownHide').multiselect({
                onDropdownHide: function(event) {
                    alert('Dropdown closed.');
                }
            });
        });
    </script>
`onDropdownShown` | A callback called after the dropdown has been shown. The `onDropdownShown` option is not available when using Twitter Bootstrap 2.3.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-onDropdownShown').multiselect({
                onDropdownShown: function(event) {
                    alert('Dropdown closed.');
                }
            });
        });
    </script>
`onDropdownHidden` | A callback called after the dropdown has been closed. The `onDropdownHidden` option is not available when using Twitter Bootstrap 2.3.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-ondropdownHidden').multiselect({
                onDropdownHidden: function(event) {
                    alert('Dropdown closed.');
                }
            });
        });
    </script>
`buttonClass` | The class of the multiselect button.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-buttonClass').multiselect({
                buttonClass: 'btn btn-link'
            });
        });
    </script>
`inheritClass` | Inherit the class of the button from the original select.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-inheritButton').multiselect({
                inheritClass: true
            });
        });
    </script>

    <select id="example-inheritButton" class="bg-warning" multiple="multiple">
        <option value="1">Option 1</option>
        <option value="2">Option 2</option>
        <option value="3">Option 3</option>
        <option value="4">Option 4</option>
        <option value="5">Option 5</option>
        <option value="6">Option 6</option>
    </select>
`buttonContainer` | The container holding both the button as well as the dropdown.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-buttonContainer').multiselect({
                buttonContainer: '<div class="btn-group" />'
            });
        });
    </script>
`buttonWidth` | The width of the multiselect button may be fixed using this option. Actually, `buttonWidth` describes the width of the `.btn-group` container and the width of the `button` is set to `100%`.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-buttonWidth').multiselect({
                buttonWidth: '400px'
            });
        });
    </script>
Note that if the text in the button title is too long, it will be truncated and use an ellipsis
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-buttonWidth-overflow').multiselect({
                buttonWidth: '150px'
            });
        });
    </script>
This does also work for long options:
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-buttonWidth-overflow').multiselect({
                buttonWidth: '150px'
            });
        });
    </script>
`buttonText` | A callback specifying the text shown on the button dependent on the currently selected options. The callback gets the currently selected `options` and the `select` as argument and returns the string shown as button text. The default `buttonText` callback returns `nonSelectedText` in the case no option is selected, `nSelectedText` in the case more than `numberDisplayed` options are selected and the names of the selected options if less than `numberDisplayed` options are selected.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-buttonText').multiselect({
                buttonText: function(options, select) {
                    if (options.length === 0) {
                        return 'No option selected ...';
                    }
                    else if (options.length > 3) {
                        return 'More than 3 options selected!';
                    }
                     else {
                         var labels = [];
                         options.each(function() {
                             if ($(this).attr('label') !== undefined) {
                                 labels.push($(this).attr('label'));
                             }
                             else {
                                 labels.push($(this).html());
                             }
                         });
                         return labels.join(', ') + '';
                     }
                }
            });
        });
    </script>
`buttonTitle` | A callback specifying the title of the button. The callback gets the currently selected `options` and the `select` as argument and returns the title of the button as string. The default `buttonTitle` callback returns `nonSelectedText` in the case no option is selected and the names of the selected options of less than `numberDisplayed` options are selected. If more than `numberDisplayed` options are selected, `nSelectedText` is returned.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-buttonTitle').multiselect({
                buttonText: function(options, select) {
                    return 'Check the title!';
                },
                buttonTitle: function(options, select) {
                    var labels = [];
                    options.each(function () {
                        labels.push($(this).text());
                    });
                    return labels.join(' - ');
                }
            });
        });
    </script>
`nonSelectedText` | The text displayed when no option is selected. This option is used in the default `buttonText` and `buttonTitle` functions.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-nonSelectedText').multiselect({
                nonSelectedText: 'Check an option!'
            });
        });
    </script>
`nSelectedText` | The text displayed if more than `numberDisplayed` options are selected. This option is used by the default `buttonText` and `buttonTitle` callbacks.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-nSelectedText').multiselect({
                nSelectedText: ' - Too many options selected!'
            });
        });
    </script>
`allSelectedText` | `allSelectedText` is the text displayed if all options are selected. You can disable displaying the `allSelectedText` by setting it to false.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-allSelectedText').multiselect({
                allSelectedText: 'No option left ...'
            });
        });
    </script>
This option may be useful in combination with the `includeSelectAllOption`:
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-allSelectedText-includeSelectAllOption').multiselect({
                includeSelectAllOption: true,
                allSelectedText: 'No option left ...'
            });
        });
    </script>
Note that the `allSelectedText` is not shown if only one option is available.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-allSelectedText-allSelectedText-single').multiselect({
                includeSelectAllOption: true,
                allSelectedText: 'No option left ...'
            });
        });
    </script>
`numberDisplayed` | This option is used by the `buttonText` and `buttonTitle` functions to determine if too many options would be displayed. The functionality can be disabled by setting `numberDisplayed` to `0`.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-numberDisplayed').multiselect({
                numberDisplayed: 1
            });
        });
    </script>
`delimiterText` | Sets the separator for the list of selected items for mouse-over. Defaults to ', '. Set to '\n' for a neater display.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-delimiterText').multiselect({
                delimiterText '; '
            });
        });
    </script>
`optionLabel` | A callback used to define the labels of the options.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-optionLabel').multiselect({
                optionLabel: function(element) {
                    return $(element).html() + '(' + $(element).val() + ')';
                }
            });
        });
    </script>
    <select id="example-label" multiple="multiple">
        <option value="option-1">Option 1</option>
        <option value="option-2">Option 2</option>
        <option value="option-3">Option 3</option>
        <option value="option-4">Option 4</option>
        <option value="option-5">Option 5</option>
        <option value="option-6">Option 6</option>
    </select>
`optionClass` | A callback used to define the classes for the `li` elements containing checkboxes and labels.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-optionClass').multiselect({
                optionClass: function(element) {
                    var value = $(element).val();

                    if (value%2 == 0) {
                        return 'even';
                    }
                    else {
                        return 'odd';
                    }
                }
            });
        });
    </script>
    <style type="text/css">
        #example-optionClass-container .multiselect-container .odd:not(.active) {
            background: #eeeeee;
        }
    </style>
    <div id="example-optionClass-container">
        <select id="example-optionClass" multiple="multiple">
            <option value="1">Option 1</option>
            <option value="2">Option 2</option>
            <option value="3">Option 3</option>
            <option value="4">Option 4</option>
            <option value="5">Option 5</option>
            <option value="6">Option 6</option>
        </select>
    </div>
`selectedClass` | The class(es) applied on selected options.
    <style type="text/css">
        #example-selectedClass-container .multiselect-selected .form-check-label {
            color: red;
        }
    </style>
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-selectedClass').multiselect({
                buttonContainer: '<div class="btn-group" id="example-selectedClass-container"></div>',
                selectedClass: 'multiselect-selected'
            });
        });
    </script>
`includeSelectAllOption` | Set to `true` or `false` to enable or disable the select all option. To see an example using both the select all option and the filter, see the documentation of the `enableFiltering` option.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-includeSelectAllOption').multiselect({
                includeSelectAllOption: true
            });
        });
    </script>
The `includeSelectAllOption` option can also be used in combination with `optgroup`'s.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-includeSelectAllOption-optgroups').multiselect({
                includeSelectAllOption: true
            });
        });
    </script>
Note that the select all does not trigger the `onChange` event and only triggers the `onSelectAll` event:
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-includeSelectAllOption-onChange').multiselect({
                includeSelectAllOption: true,
                onChange: function(option, checked) {
                    alert('Not triggered when clicking the select all!');
                },
            });
        });
    </script>
The select all element naturally respects disabled elements:
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-includeSelectAllOption-disbled').multiselect({
                includeSelectAllOption: true
            });
        });
    </script>
`selectAllJustVisible` | Setting both `includeSelectAllOption` and `enableFiltering` to `true`, the select all option does always select only the visible option. With setting `selectAllJustVisible` to `false` this behavior is changed such that always all options (irrespective of whether they are visible) are selected.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-selectAllJustVisible').multiselect({
                enableFiltering: true,
                includeSelectAllOption: true,
                selectAllJustVisible: false
            });
        });
    </script>
`selectAllText` | The text displayed for the select all option.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-selectAllText').multiselect({
                includeSelectAllOption: true,
                selectAllText: 'Check all!'
            });
        });
    </script>
`selectAllValue` | The select all option is added as additional `option` within the `select`. To distinguish this option from the original options the value used for the select all option can be configured using the `selectAllValue` option.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-selectAllValue').multiselect({
                includeSelectAllOption: true,
                selectAllValue: 'select-all-value'
            });
        });
    </script>
The `selectAllValue` option should usually be a string, however, numeric values work as well:
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-selectAllValue-numeric').multiselect({
                includeSelectAllOption: true,
                selectAllValue: 0
            });
        });
    </script>
`selectAllName` | This option allows to control the name given to the select all option. See Server-Side Processing for more details.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-selectAllName').multiselect({
                includeSelectAllOption: true,
                selectAllName: 'select-all-name'
            });
        });
    </script>
`selectAllNumber` | If set to `true` (default), the number of selected options will be shown in parantheses when all options are seleted. The below example shows the behavior of the selectalloption with `selectAllNumber` set to `false`:
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-selectAllNumber').multiselect({
                includeSelectAllOption: true,
                selectAllNumber: false
            });
        });
    </script>
`onSelectAll` | This function is triggered when the select all option is used to select all options. Note that this can also be triggered manually using the `.multiselect('selectAll')` method. Note that the `onChange` option is not triggered when (de)selecting all options using the select all option. The `onSelectAll` option is only triggered if the select all option was checked; it is not triggered if all options were checked manually (causing the select all option to be checked as well).
    <script type="text/javascript">
        $('#example-onSelectAll').multiselect({
            includeSelectAllOption: true,
            onSelectAll: function() {
                alert('onSelectAll triggered!');
            }
        });
    </script>
`onDeselectAll` | This function is triggered when the select all option is used to deselect all options. Note that this can also be triggered manually using the `.multiselect('deselectAll')` method. Note that the `onChange` option is not triggered when (de)selecting all options using the select all option. The `onDeselectAll` option is only triggered if the select all option was unchecked; it is not triggered if all options were unchecked manually (causing the select all option to be unchecked as well).
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-onDeselectAll').multiselect({
                includeSelectAllOption: true,
                onDeselectAll: function() {
                    alert('onDeselectAll triggered!');
                }
            });
        });
    </script>
`enableFiltering` | Set to `true` or `false` to enable or disable the filter. A filter `input` will be added to dynamically filter all options.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-enableFiltering').multiselect({
                enableFiltering: true
            });
        });
    </script>
The `enableFiltering` option can easily be used in combination with the `includeSelectAllOption` option:
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-enableFiltering-includeSelectAllOption').multiselect({
                includeSelectAllOption: true,
                enableFiltering: true
            });
        });
    </script>
The `enableFiltering` option can also be used in combination with `optgroup`'s.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-example-enableFiltering-optgroups').multiselect({
                enableFiltering: true
            });
        });
    </script>
Clickable `optgroup`'s are also supported:
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-example-enableFiltering-enableClickableOptgroups').multiselect({
                enableFiltering: true,
                enableClickableOptGroups: true
            });
        });
    </script>
Finally, the option can also be used together with `onChange` or similar events:
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-enableFiltering-onChange-onDropdownHide').multiselect({
                enableFiltering: true,
                onChange: function(option, checked) {
                    alert('onChange!');
                },
                onDropdownHide: function(event) {
                    alert('onDropdownHide!');
                }
            });
        });
    </script>
`enableCaseInsensitiveFiltering` | The filter as configured above will use case sensitive filtering, by setting `enableCaseInsensitiveFiltering` to `true` this behavior can be changed to use case insensitive filtering.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-enableCaseInsensitiveFiltering').multiselect({
                enableCaseInsensitiveFiltering: true
            });
        });
    </script>
`enableFullValueFiltering` | Set to `true` to enable full value filtering, that is all options are shown where the query is a prefix of. An example is given here: #555.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-enableFullValueFiltering').multiselect({
                enableFiltering: true,
                enableFullValueFiltering: true
            });
        });
    </script>
`filterBehavior` | The options are filtered based on their `text`. This behavior can be changed to use the `value` of the options or `both` the text and the value. In this example, the options have values from `a` to `n`. Instead of searching the text of the options, the value of the options is searched.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-filterBehavior').multiselect({
                enableFiltering: true,
                filterBehavior: 'value'
            });
        });
    </script>
    <select id="example-filterBehavior" multiple="multiple">
        <option value="a">Option 1</option>
        <option value="b">Option 2</option>
        <option value="c">Option 3</option>
        <option value="d">Option 4</option>
        <option value="e">Option 5</option>
        <option value="f">Option 6</option>
        <option value="g">Option 7</option>
        <option value="h">Option 8</option>
        <option value="i">Option 9</option>
        <option value="j">Option 10</option>
        <option value="k">Option 11</option>
        <option value="l">Option 12</option>
        <option value="m">Option 13</option>
        <option value="n">Option 14</option>
    </select>
`filterPlaceholder` | The placeholder used for the filter input.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-filter-placeholder').multiselect({
                enableFiltering: true,
                filterPlaceholder: 'Search for something...'
            });
        });
    </script>
`includeResetOption` | Add reset button to dropdown.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-include-reset-option').multiselect({
                includeResetOption: true
            });
        });
    </script>
`includeResetDivider` | Add a divider between reset button and options.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-include-reset-divider').multiselect({
                includeResetOption: true,
                includeResetDivider: true
            });
        });
    </script>
`resetText` | Add reset button to dropdown.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-reset-text').multiselect({
                includeResetOption: true,
                resetText: "Reset all"
            });
        });
    </script>

## Templates

The generated HTML markup can be controlled using templates. Basically, templates are simple configuration options. The default templates are shown below:

However, note that messing with the template's classes may cause unexpected behavior. For example the button should always have the class `.multiselect`,

In addition, note that other options may also have influence on the templates, for example the `buttonClass` option.

    <script type="text/javascript">
        $(document).ready(function() {
            $('#example').multiselect({
                templates: {
                    button: '<button type="button" class="multiselect dropdown-toggle" data-toggle="dropdown"><span class="multiselect-selected-text"></span></button>',
                    ul: '<div class="multiselect-container dropdown-menu"></div>',
                    filter: '<div class="multiselect-item multiselect-filter"><div class="input-group input-group-sm p-1"><div class="input-group-prepend"><i class="input-group-text fas fa-search"></i></div><input class="form-control multiselect-search" type="text"></div></div>',
                    filterClearBtn: '<div class="input-group-append"><button class="multiselect-clear-filter input-group-text" type="button"><i class="fas fa-times"></i></button></div>',
                    li: '<a class="multiselect-option dropdown-item"></a>',
                    divider: '<div class="multiselect-item dropdown-divider"></div>',
                    liGroup: '<a class="multiselect-item multiselect-group"></a>',
                    resetButton: '<div class="multiselect-reset text-center p-2"><a class="btn btn-sm btn-block btn-outline-secondary"></a></div>'
                }
            });
        });
    </script>

For example other elements instead of buttons may be used by adapting the template:

    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-templates-button').multiselect({
                buttonContainer: '<div></div>',
                buttonContainer: '',
                buttonClass: '',
                templates: {
                    button: '<span class="multiselect dropdown-toggle" data-toggle="dropdown">Click me!</span>'
                }
            });
        });
    </script>
    <style type="text/css">
        span.multiselect {
            padding: 2px 6px;
            font-weight: bold;
            cursor: pointer;
        }
    </style>

The most interesting template is the `li` template as it allows to customize the displayed options; for example (see #738 for details) to include input elements in the options:

    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-templates-input').multiselect({
                templates: {
                    li: '<a class"multiselect-option dropdown-item"><a><label style="display:inline;"></label><input type="text" /></a></a>'
                }
            });
        });
    </script>

## Styling

The style of the plugin is fully adaptable through CSS; a completely rendered example is shown below - including select all option, filter and option groups.

    <div class="multiselect-container dropdown-menu show">
        <div class="multiselect-item multiselect-filter">
            <div class="input-group input-group-sm p-1">
                <div class="input-group-prepend">
                    <i class="input-group-text fas fa-search"></i>
                </div>
                <input class="form-control multiselect-search" type="text" placeholder="Search">
                <div class="input-group-append">
                    <button class="multiselect-clear-filter input-group-text" type="button">
                        <i class="fas fa-times"></i>
                    </button>
                </div>
            </div>
        </div>
        <a class="multiselect-option dropdown-item multiselect-item multiselect-all">
            <span class="form-check d-inline-flex" title="Select all">
                <input class="form-check-input" type="checkbox" value="multiselect-all">
                <label class="form-check-label font-weight-bold">Select all</label>
            </span>
        </a>
        <div class="multiselect-reset text-center p-2">
            <a class="btn btn-sm btn-block btn-outline-secondary">Reset</a>
        </div>
        <div class="multiselect-item dropdown-divider mt-0"></div>
        <a class="multiselect-item multiselect-group dropdown-item">
            <input type="checkbox" value="undefined">
            Fruits
            <span class="caret-container dropdown-toggle pl-1"></span>
        </a>
        <a class="multiselect-option dropdown-item">
            <span class="form-check d-inline-flex" title="Apple">
                <input class="form-check-input" type="checkbox" value="Apple">
                <label class="form-check-label">Apple</label>
            </span></a>
        <a class="multiselect-option dropdown-item">
            <span class="form-check d-inline-flex" title="Banana">
                <input class="form-check-input" type="checkbox" value="Banana">
                <label class="form-check-label">Banana</label>
            </span>
        </a>
        <a class="multiselect-item multiselect-group dropdown-item">
            <input type="checkbox" value="undefined">
            Vegetables
            <span class="caret-container dropdown-toggle pl-1"></span>
        </a>
        <a class="multiselect-option dropdown-item">
            <span class="form-check d-inline-flex" title="Potato">
                <input class="form-check-input" type="checkbox" value="Potato">
                <label class="form-check-label">Potato</label>
            </span>
        </a>
        <a class="multiselect-option dropdown-item">
            <span class="form-check d-inline-flex" title="Parsnip">
                <input class="form-check-input" type="checkbox" value="Parsnip">
                <label class="form-check-label">Parsnip</label>
            </span>
        </a>
    </div>

The most important classes are: `multiselect-container`, `multiselect-filter`, `multiselect-all`, `multiselect-item`, `multiselect-group`, `multiselect-option` as well as `disabled` and `active`. Both for collapsing and filtering options, the classes `multiselect-filter-hidden` and `multiselect-collapsible-hidden` are used.

## Methods

`.multiselect('destroy')` | This method is used to destroy the plugin on the given element - meaning unbinding the plugin.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-destroy').multiselect();
            $('#example-destroy-button').on('click', function() {
                $('#example-destroy').multiselect('destroy');
            });
        });
    </script>
`.multiselect('refresh')` | This method is used to refresh the checked checkboxes based on the currently selected options within the `select`. Click 'Select some options' to select some of the options. Then click refresh. The plugin will update the checkboxes accordingly.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-refresh').multiselect();

            $('#example-refresh-select').on('click', function() {
                $('option[value="1"]', $('#example-refresh')).prop('selected', true);
                $('option[value="3"]', $('#example-refresh')).prop('selected', true);
                $('option[value="4"]', $('#example-refresh')).prop('selected', true);

                alert('Option 1, 2 and 4.');
            });

            $('#example-refresh-deselect').on('click', function() {
                $('option', $('#example-refresh')).each(function(element) {
                    $(this).removeAttr('selected').prop('selected', false);
                });
            });

            $('#example-refresh-button').on('click', function() {
                $('#example-refresh').multiselect('refresh');
            });
        });
    </script>
`.multiselect('rebuild')` | Rebuilds the whole dropdown menu. All selected options will remain selected (if still existent!).
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-rebuild').multiselect();

            $('#example-rebuild-button').on('click', function() {
                $('#example-rebuild').multiselect('rebuild');
            });

            $('#example-rebuild-add').on('click', function() {
                $('#example-rebuild').append('<option value="add1">Addition 1</option>
    <option value="add2">Addition 2</option><option value="add3">Addition 3</option>');
            });

            $('#example-rebuild-delete').on('click', function() {
                $('option[value="add1"]', $('#example-rebuild')).remove();
                $('option[value="add2"]', $('#example-rebuild')).remove();
                $('option[value="add3"]', $('#example-rebuild')).remove();
            });
        });
    </script>
`.multiselect('select', value)` | Selects an option by its value. Works also using an array of values.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-select').multiselect();

            $('#example-select-button').on('click', function() {
                $('#example-select').multiselect('select', ['1', '2', '4']);

                alert('Selected 1, 2 and 4.');
            });
        });
    </script>
The method provides an additional parameter: `.multiselect('select', value, triggerOnChange)`. If the second parameter is set to true, the method will manually trigger the `onChange` option.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-select-onChange').multiselect({
                onChange: function(option, checked, select) {
                    alert('onChange triggered ...');
                }
            });

            $('#example-select-onChange-button').on('click', function() {
                $('#example-select-onChange').multiselect('select', '1', true);
            });
        });
    </script>
The above parameter does also work when selecting multipe values. Note that `onChange` is called for each selected option individually!
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-select-onChange-array').multiselect({
                onChange: function(option, checked, select) {
                    alert('onChange triggered ...');
                }
            });

            $('#example-select-onChange-array-button').on('click', function() {
                $('#example-select-onChange-array').multiselect('select', ['1', '3'], true);
            });
        });
    </script>
`.multiselect('deselect', value)` | Deselect an option by its value. Works also using an array of values.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-deselect').multiselect();

            $('#example-deselect-button').on('click', function() {
                $('#example-deselect').multiselect('deselect', ['1', '2', '4']);

                alert('Deselected 1, 2 and 4.');
            });
        });
    </script>
The method provides an additional parameter: `.multiselect('deselect', value, triggerOnChange)`. If the second parameter is set to true, the method will manually trigger the `onChange` option.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-deselect-onChange').multiselect({
                onChange: function(option, checked, select) {
                    alert('onChange triggered ...');
                }
            });

            $('#example-deselect-onChange-button').on('click', function() {
                $('#example-deselect-onChange').multiselect('deselect', '1', true);
            });
        });
    </script>
The above parameter does also work when deselecting multiple options. Note that `onChange` is called for each deselected option individually.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-deselect-onChange-array').multiselect({
                onChange: function(option, checked, select) {
                    alert('onChange triggered ...');
                }
            });

            $('#example-deselect-onChange-array-button').on('click', function() {
                $('#example-deselect-onChange-array').multiselect('deselect', ['1', '3'], true);
            });
        });
    </script>
`.multiselect('selectAll', justVisible)` | Selects all options. If `justVisible` is set to `true` or not provided, all visible options are selected (when using the filter), otherweise (`justVisible` set to `false`) all options are selected. Note that setting `justVisible` to `true`, or providing no parameter will select all visible options, that is the dropdown needs to be opened. Currently, it is required to call `.multiselect('updateButtonText')` manually after calling `.multiselect('selectAll', justVisible)`.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-selectAll').multiselect({
                includeSelectAllOption: true
            });

            $('#example-selectAll-visible').on('click', function() {
                $('#example-selectAll').multiselect('selectAll', true);
            });
            $('#example-selectAll-all').on('click', function() {
                $('#example-selectAll').multiselect('selectAll', false);
            });
        });
    </script>
`.multiselect('deselectAll', justVisible)` | Deselects all options. If `justVisible` is set to `true` or not provided, all visible options are deselected, otherweise (`justVisible` set to `false`) all options are deselected. Note that setting `justVisible` to `true`, or providing no parameter will select all visible options, that is the dropdown needs to be opened. Currently, it is required to call `.multiselect('updateButtonText')` manually after calling `.multiselect('selectAll', justVisible)`.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-deselectAll').multiselect({
                includeSelectAllOption: true
            });

            $('#example-deselectAll-visible').on('click', function() {
                $('#example-deselectAll').multiselect('deselectAll', true);
            });
            $('#example-deselectAll-all').on('click', function() {
                $('#example-deselectAll').multiselect('deselectAll', false);
            });
        });
    </script>
`.multiselect('updateButtonText')` | When manually selecting/deselecting options and the corresponding checkboxes, this function updates the text and title of the button. Note that usually this method is only needed when using `.multiselect('selectAll', justVisible)` or `.multiselect('deselectAll', justVisible)`. In all other cases, `.multiselect('refresh')` should be used.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-updateButtonText').multiselect({
                buttonContainer: ''
            });

            $('#example-updateButtonText-select').on('click', function() {
                $('option[value="1"]', $('#example-updateButtonText')).prop('selected', true);
                $('option[value="3"]', $('#example-updateButtonText')).prop('selected', true);

                $('input[value="1"]', $('#example-updateButtonText-container')).prop('checked', true);
                $('input[value="3"]', $('#example-updateButtonText-container')).prop('checked', true);

                $('input[value="1"]', $('#example-updateButtonText-container')).closest('.multiselect-option').addClass('active');
                $('input[value="3"]', $('#example-updateButtonText-container')).closest('.multiselect-option').addClass('active');
            });
            $('#example-updateButtonText-update').on('click', function() {
                $('#example-updateButtonText').multiselect('updateButtonText');
            });
        });
    </script>
`.multiselect('setOptions', options)` | Used to change configuration after initializing the multiselect. This may be useful in combination with `.multiselect('rebuild')`.
    <script type="text/javascript">
        $(document).ready(function() {

            var firstConfigurationSet = {
                includeSelectAllOption: false,
                enableFiltering: false
            };
            var secondConfigurationSet = {
                includeSelectAllOption: false,
                enableFiltering: true
            };

            var set = 1;
            $('#example-setOptions').multiselect(firstConfigurationSet);

            function rebuildMultiselect(options) {
                $('#example-setOptions').multiselect('setOptions', options);
                $('#example-setOptions').multiselect('rebuild');
            }

            $('#example-setOptions-button').on('click', function(event) {
                switch (set) {
                    case 2:
                        rebuildMultiselect(firstConfigurationSet);

                        $(this).text('Configuration Set 2');
                        set = 1;
                        break;
                    case 1:
                    default:
                        rebuildMultiselect(secondConfigurationSet);

                        $(this).text('Configuration Set 1');
                        set = 2;
                        break;

                }
            });
        });
    </script>
`.multiselect('disable')` | Disable both the underlying select and the dropdown button.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-disable').multiselect();

            $('#example-disable-button').on('click', function() {
                $('#example-disable').multiselect('disable');
            });
        });
    </script>
`.multiselect('enable')` | Enable both the underlying select and the dropdown button.
    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-enable').multiselect();

            $('#example-enable-button').on('click', function() {
                $('#example-enable').multiselect('enable');
            });
        });
    </script>
`.multiselect('dataprovider', data)` | This method is used to provide options programmatically. See the example below.
    <script type="text/javascript">
        $('#example-dataprovider').multiselect();

        var options = [
            {label: 'Option 1', title: 'Option 1', value: '1', selected: true},
            {label: 'Option 2', title: 'Option 2', value: '2'},
            {label: 'Option 3', title: 'Option 3', value: '3', selected: true},
            {label: 'Option 4', title: 'Option 4', value: '4'},
            {label: 'Option 5', title: 'Option 5', value: '5'},
            {label: 'Option 6', title: 'Option 6', value: '6', disabled: true}
        ];
        $('#example-dataprovider').multiselect('dataprovider', options);
    </script>
    <select id="example-dataprovider" multiple="multiple"></select>
The method is also able to handle `optgroup`'s:
    <script type="text/javascript">
        $('#example-dataprovider-optgroups').multiselect();

        var optgroups = [
            {
                label: 'Group 1', children: [
                    {label: 'Option 1.1', value: '1-1', selected: true},
                    {label: 'Option 1.2', value: '1-2'},
                    {label: 'Option 1.3', value: '1-3'}
                ]
            },
            {
                label: 'Group 2', children: [
                    {label: 'Option 2.1', value: '1'},
                    {label: 'Option 2.2', value: '2'},
                    {label: 'Option 2.3', value: '3', disabled: true}
                ]
            }
        ];
        $('#example-dataprovider-optgroups').multiselect('dataprovider', optgroups);
    </script>
    <select id="example-dataprovider-optgroups" multiple="multiple"></select>
You can add custom data attributes on option group children and non-grouped options:
          $('#example-dataprovider-data-attributes').multiselect();

          var optionsData =[
                          {
                            "label": "Option 1",
                            "value": 1,
                            "selected": true,
                            "attributes": {
                              "some-attribute": 1,
                              "another-attribute": false
                            }
                          },
                          {
                            "label": "Option 2",
                            "value": 2,
                            "selected": false,
                            "attributes": {
                              "some-attribute": 2
                            }
                          }
                        ];
            $("#example-dataprovider-data-attributes").multiselect('dataprovider', optionsData);
        });
    </script>
    <select id="example-dataprovider-data-attributes" multiple="multiple"></select>
Renders as:
    <option value="1" label="Option 1" selected="selected" data-some-attribute="1" data-another-attribute="false"></option>
    <option value="2" label="Option 2" data-some-attribute="2"></option>
`.multiselect('setAllSelectedText', value)` | This method is used to programmatically provide a new text to display in the button when all options are selected, at runtime.
    <script type="text/javascript">
        $('#example-set-all-selected-text').multiselect({allSelectedText: "Initial All Selected"});

        $('#new-all-selected-text-btn').click(function(){
            $('#example-set-all-selected-text').multiselect('setAllSelectedText', $('#new-all-selected-text-box').val());
        });
    </script>

## Further Examples

Using the `onChange` configuration option, the following example asks for confirmation if deselecting an option.

    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-confirmation').multiselect({
                onChange: function(element, checked) {
                    if (checked === true) {
                        //action taken here if true
                    }
                    else if (checked === false) {
                        if (confirm('Do you wish to deselect the element?')) {
                            //action taken here
                        }
                        else {
                            $("#example-confirmation").multiselect('select', element.val());
                        }
                    }
                }
            });
        });
    </script>

The above approach can also be adapted to be used in

    <script type="text/javascript">
        $(document).ready(function() {
            var lastSelected = $('#example-confirmation-single option:selected').val();
            $('#example-confirmation-single').multiselect({
                onChange: function(element, checked) {
                    if (confirm('Do you wish to change the selection?')) {
                        lastSelected = element.val();
                    }
                    else {
                        $("#example-confirmation-single").multiselect('select', lastSelected);
                        $("#example-confirmation-single").multiselect('deselect', element.val());
                    }
                }
            });
        });
    </script>

Limit the number of selected options using the `onChange` option. The user may only select a maximum of 4 options. Then all other options are disabled.

    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-limit').multiselect({
                onChange: function(option, checked) {
                    // Get selected options.
                    var selectedOptions = $('#example-limit option:selected');

                    if (selectedOptions.length >= 4) {
                        // Disable all other checkboxes.
                        var nonSelectedOptions = $('#example-limit option').filter(function() {
                            return !$(this).is(':selected');
                        });

                        nonSelectedOptions.each(function() {
                            var input = $('input[value="' + $(this).val() + '"]');
                            input.prop('disabled', true);
                            input.parent('.multiselect-option').addClass('disabled');
                        });
                    }
                    else {
                        // Enable all checkboxes.
                        $('#example-limit option').each(function() {
                            var input = $('input[value="' + $(this).val() + '"]');
                            input.prop('disabled', false);
                            input.parent('.multiselect-option').addClass('disabled');
                        });
                    }
                }
            });
        });
    </script>

Record the order the options are selected. When selecting an item an ordering number will be incremented and saved within the option.

    <script type="text/javascript">
        $(document).ready(function() {
            var orderCount = 0;
            $('#example-order').multiselect({
                onChange: function(option, checked) {
                    if (checked) {
                        orderCount++;
                        $(option).data('order', orderCount);
                    }
                    else {
                        $(option).data('order', '');
                    }
                },
                buttonText: function(options) {
                    if (options.length === 0) {
                        return 'None selected';
                    }
                    else if (options.length > 3) {
                        return options.length + ' selected';
                    }
                    else {
                        var selected = [];
                        options.each(function() {
                            selected.push([$(this).text(), $(this).data('order')]);
                        });

                        selected.sort(function(a, b) {
                            return a[1] - b[1];
                        });

                        var text = '';
                        for (var i = 0; i < selected.length; i++) {
                            text += selected[i][0] + ', ';
                        }

                        return text.substr(0, text.length -2);
                    }
                },
            });

            $('#example-order-button').on('click', function() {
                var selected = [];
                $('#example-order option:selected').each(function() {
                    selected.push([$(this).val(), $(this).data('order')]);
                });

                selected.sort(function(a, b) {
                    return a[1] - b[1];
                });

                var text = '';
                for (var i = 0; i < selected.length; i++) {
                    text += selected[i][0] + ', ';
                }
                text = text.substring(0, text.length - 2);

                alert(text);
            });
        });
    </script>

Simulate single selections using checkboxes. The behavior will be similar to a multiselect with radio buttons except that the selected option can be deselected again.

    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-simulate-single').multiselect({
                on: {
                    change: function(option, checked) {
                        var values = [];
                        $('#example-simulate-single option').each(function() {
                            if ($(this).val() !== option.val()) {
                                values.push($(this).val());
                            }
                        });

                        $('#example-simulate-single').multiselect('deselect', values);
                    }
                }
            });
        });
    </script>

Using a reset button together with a multiselect.

    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-reset').multiselect();
            $('#example-reset-form').on('reset', function() {
                $('#example-reset option:selected').each(function() {
                    $(this).prop('selected', false);
                })

                $('#example-reset').multiselect('refresh');
            });
        });
    </script>
    <form class="btn-group" id="example-reset-form">
        <div class="btn-group">
            <select id="example-reset" multiple="multiple">
                <option value="1">Option 1</option>
                <option value="2">Option 2</option>
                <option value="3">Option 3</option>
                <option value="4">Option 4</option>
                <option value="5">Option 5</option>
                <option value="6">Option 6</option>
            </select>
            <button type="reset" id="example-reset-button" class="btn btn-default">Reset</button>
        </div>
    </form>

Multiselect can also be used in modals:

##### Bootstrap Multiselect

    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-modal').multiselect();
        });
    </script>
    <button class="btn btn-outline-secondary" data-toggle="modal" data-target="#example-modal-modal">Launch modal</button>
    <div class="modal fade" id="example-modal-modal">
        <div class="modal-dialog">
            <div class="modal-content">
                <div class="modal-header">
                    <h5 class="modal-title">Bootstrap Multiselect</h5>
                    <button type="button" class="close" data-dismiss="modal"><span aria-hidden="true">×</span><span class="sr-only">Close</span></button>
                </div>
                <div class="modal-body">
                    <select id="example-modal" multiple="multiple">
                        <option value="1">Option 1</option>
                        <option value="2">Option 2</option>
                        <option value="3">Option 3</option>
                        <option value="4">Option 4</option>
                        <option value="5">Option 5</option>
                        <option value="6">Option 6</option>
                    </select>
                </div>
            </div>
        </div>
    </div>

An example of using multiselect in an accordion/collapse:

Note that the overflow of the `.card` needs to be visible: `style="overflow:visible;"`. See the example below.

##

    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-collapse').multiselect();
        });
    </script>
    <div class="accordion" id="example-collapse-accordion">
        <div class="card" style="overflow:visible;">
            <div class="card-header">
                <h2 class="mb-0">
                    <button class="btn btn-link btn-block text-left" data-toggle="collapse" data-target="#example-collapse-accordion-one">
                        Bootstrap Multiselect
                    </button>
                </h2>
            </div>
            <div id="example-collapse-accordion-one" class="collapse show">
                <div class="card-body">
                    <select id="example-collapse" multiple="multiple">
                        <option value="1">Option 1</option>
                        <option value="2">Option 2</option>
                        <option value="3">Option 3</option>
                        <option value="4">Option 4</option>
                        <option value="5">Option 5</option>
                        <option value="6">Option 6</option>
                    </select>
                </div>
            </div>
        </div>
    </div>

The examples below are aimed to demonstrate the performance of several features when using a large number of options:

- Using the select all option, `includeSelectAllOption` set to `true`.
- Additionally using a filter, `enableFiltering` set to `true`.
- Additionally using `enableClickableOptGroups`.
- Resetting the multiselect.

The below examples need to be activated. Note that this may take some time!

Use options:

    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-large-enable').on('click', function() {
                var options = $('#example-large-options').val();

                if (options < 1 || options > 5000) {
                    $('#example-large-error').html('<p class="alert alert-error">Choose between 1 and 5000 options!</p>');
                }
                else {
                    $('#example-large-includeSelectAllOption').html('');
                    $('#example-large-includeSelectAllOption-enableFiltering').html('');
                    $('#example-large-includeSelectAllOption-enableFiltering-enableClickableOptGroups').html('');
                    $('#example-large-reset').html('');

                    for (var j = 0; j < options; j++) {
                        i = j + 1;
                        $('#example-large-includeSelectAllOption').append('<option value="' + i.toString() + '">Option ' + i.toString() + '</option>');
                        $('#example-large-includeSelectAllOption-enableFiltering').append('<option value="' + i.toString() + '">Option ' + i.toString() + '</option>');

                        var group = Math.floor(j/10) + 1;
                        var number = j % 10 + 1;
                        if (number === 1) {
                            $('#example-large-includeSelectAllOption-enableFiltering-enableClickableOptGroups').append('<optgroup label="Group ' + group.toString() + '"></optgroup>');
                        }
                        $('#example-large-includeSelectAllOption-enableFiltering-enableClickableOptGroups').append('<option value="' + group.toString() + '-' + number.toString() + '">Option ' + group.toString() + '.' + number.toString() + '</option>');

                        $('#example-large-reset').append('<option value="' + i.toString() + '">Option ' + i.toString() + '</option>');
                    }

                    $('#example-large-includeSelectAllOption').multiselect({
                        maxHeight: 200,
                        includeSelectAllOption: true
                    });

                    $('#example-large-includeSelectAllOption-enableFiltering').multiselect({
                        maxHeight: 200,
                        includeSelectAllOption: true,
                        enableFiltering: true
                    });

                    $('#example-large-includeSelectAllOption-enableFiltering-enableClickableOptGroups').multiselect({
                        maxHeight: 200,
                        includeSelectAllOption: true,
                        enableFiltering: true,
                        enableClickableOptGroups: true
                    });

                    $('#example-large-reset').multiselect({
                        maxHeight: 200,
                        includeSelectAllOption: true
                    });

                    $('#example-large-reset-form').on('reset', function() {
                        $('#example-large-reset').multiselect('deselectAll', false);
                        $('#example-large-reset').multiselect('updateButtonText');
                    });
                }
            });
        });
    </script>
    <div class="btn-toolbar" style="margin-bottom:12px;">
        <div class="btn-group">
            <select id="example-large-includeSelectAllOption" multiple="multiple">
                <option value="1">Option 1</option>
            </select>
        </div>
    </div>
    <div class="btn-toolbar" style="margin-bottom:12px;">
        <div class="btn-group">
            <select id="example-large-includeSelectAllOption-enableFiltering" multiple="multiple">
                <option value="1">Option 1</option>
            </select>
        </div>
    </div>
    <div class="btn-toolbar" style="margin-bottom:12px;">
        <div class="btn-group">
            <select id="example-large-includeSelectAllOption-enableFiltering-enableClickableOptGroups" multiple="multiple">
                <option value="1">Option 1</option>
            </select>
        </div>
    </div>
    <form id="example-large-reset-form" style="margin-bottom:12px;">
        <select id="example-large-reset" multiple="multiple">
            <option value="1">Option 1</option>
        </select>
        <button type="reset" class="btn btn-default">Reset</button>
    </form>

The following examples is aimed to demonstrate the performance of the `.multiselect('dataprovider', data)` for a large number of options.

The below examples need to be activated. Note that this may take some time!

    $(document).ready(function() {
        var data = [];
        for (var i = 0; i < 100; i++) {
            var group = {label: 'Group ' + (i + 1), children: []};
            for (var j = 0; j < 10; j++) {
                group['children'].push({
                    label: 'Option ' + (i + 1) + '.' + (j + 1),
                    value: i + '-' + j
                });
            }

            data.push(group);
        }

        $('#example-large-dataprovider-button').on('click', function() {
            $('#example-large-dataprovider').multiselect({
                maxHeight: 200
            });
            $('#example-large-dataprovider').multiselect('dataprovider', data);
        });
    });
    <p class="alert alert-info"><button id="example-large-dataprovider-button" class="btn btn-primary">Activate</button></p>
    <select id="example-large-dataprovider" multiple="multiple"></select>

The following example illsutrates how to disable options using JavaScript.

    $(document).ready(function() {
        $('#example-disable-javascript').multiselect();
    });
    <select id="example-disable-javascript" multiple="multiple"></select>

Performance example for using `.multiselect('refresh')` with a large number of options:

The below examples need to be activated. Note that this may take some time!

    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-large-refresh-button').on('click', function() {
                for (var i = 0; i < 1000; i++) {
                    $('#example-large-refresh').append('<option value="' + i + '">Option ' + i + '</option>');
                }

                $('#example-large-refresh').multiselect();
            });

            $('#example-large-refresh-refresh').on('click', function() {
                $('#example-large-refresh').multiselect('refresh');
            });

            $('#example-large-refresh-select').on('click', function() {
                var count = 0;

                $('#example-large-refresh option').each(function() {
                    var i = $(this).val();

                    if (i%2 == 0) {
                        $(this).prop('selected', true);
                        count++;
                    }

                });

                alert('Selected ' + count + ' options!');
            });
        });
    </script>

The following example demonstrates how to limit the number of selections of a specific `optgroup`:

    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-optgroup-limit').multiselect({
                onChange: function(options, checked) {
                    var $option = $(options);
                    if ($option.length == 1) {

                        var $group = $option.parent('optgroup')
                        if ($group.hasClass('group-1')) {
                            var $options = $('option', $group);
                            $options = $options.filter(':selected');

                            if (checked && $options.length > 2) {
                                alert('Cannot select more than 2 elements in this group!');
                                $("#example-optgroup-limit").multiselect('deselect', $option.val());
                            }
                        }
                    }
                }
            });
        });
    </script>
    <div class="btn-group">
        <select id="example-optgroup-limit" multiple="multiple">
            <optgroup class="group-1" label="Group 1">
                <option value="1-1">Option 1.1</option>
                <option value="1-2">Option 1.2</option>
                <option value="1-3">Option 1.3</option>
            </optgroup>
            <optgroup class="group-2" label="Group 2">
                <option value="2-1">Option 2.1</option>
                <option value="2-2">Option 2.2</option>
                <option value="2-3">Option 2.3</option>
            </optgroup>
        </select>
    </div>

The below example demonstrates how to show the `optgroup`'s label if all `option`'s within this group are selected:

    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-optgroup-buttonText').multiselect({
                buttonText: function(options, select) {

                    // First consider the simple cases, i.e. disabled and empty.
                    if (this.disabledText.length > 0
                            && (this.disableIfEmpty || select.prop('disabled'))
                            && options.length == 0) {

                        return this.disabledText;
                    }
                    else if (options.length === 0) {
                        return this.nonSelectedText;
                    }

                    var $select = $(select);
                    var $optgroups = $('optgroup', $select);

                    var delimiter = this.delimiterText;
                    var text = '';

                    // Go through groups.
                    $optgroups.each(function() {
                        var $selectedOptions = $('option:selected', this);
                        var $options = $('option', this);

                        if ($selectedOptions.length == $options.length) {
                            text += $(this).attr('label') + delimiter;
                        }
                        else {
                            $selectedOptions.each(function() {
                                text += $(this).text() + delimiter;
                            });
                        }
                    });

                    var $remainingOptions = $('option:selected', $select).not('optgroup option');
                    $remainingOptions.each(function() {
                        text += $(this).text() + delimiter;
                    });

                    return text.substr(0, text.length - 2);
                }
            });
        });
    </script>
    <div class="btn-group">
        <select id="example-optgroup-buttonText" multiple="multiple">
            <optgroup class="group-1" label="Group 1">
                <option value="1-1">Option 1.1</option>
                <option value="1-2">Option 1.2</option>
                <option value="1-3">Option 1.3</option>
            </optgroup>
            <optgroup class="group-2" label="Group 2">
                <option value="2-1">Option 2.1</option>
                <option value="2-2">Option 2.2</option>
                <option value="2-3">Option 2.3</option>
            </optgroup>
        </select>
    </div>

The following example demonstrates how to set the class `active` of `input`'s parent element:

    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-selected-parents').multiselect({
                buttonContainer: '<div id="example-selected-parents-container"></div>',
                onChange: function(options, selected) {
                    // Get checkbox corresponding to option:
                    var value = $(options).val();
                    var $input = $('#example-selected-parents-container input[value="' + value + '"]');

                    // span label class:
                    if (selected) {
                        $input.closest('span').addClass('active');
                    }
                    else {
                        $input.closest('span').removeClass('active');
                    }
                }
            });
        });
    </script>
    <style type="text/css">
        #example-selected-parents-container span.active {
            font-weight: bold;
        }
    </style>
    <div class="btn-group">
        <select id="example-selected-parents" multiple="multiple">
            <option value="1">Option 1</option>
            <option value="2">Option 2</option>
            <option value="3">Option 3</option>
            <option value="4">Option 4</option>
            <option value="5">Option 5</option>
            <option value="6">Option 6</option>
        </select>
    </div>

The following example demonstrates how to clear filtering as soon as an option is selected after the filter was used. Note that the filter is cleared both when an option is selected and deselected.

    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-clear-after-filter-selection').multiselect({
                buttonContainer: '',
                enableFiltering: true,
                onChange: function($option) {
                    // Check if the filter was used.
                    var query = $('#example-clear-after-filter-selection-container .multiselect-filter input').val();

                    if (query) {
                        $('#example-clear-after-filter-selection-container .multiselect-filter input').val('').trigger('keydown');
                    }
                }
            });
        });
    </script>

The following example demonstrates how to display a list of checkboxes without a dropdown:

    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-checkbox-list').multiselect({
                buttonContainer: '<div id="example-checkbox-list-container"></div>',
                buttonClass: '',
                templates: {
                    button: '',
                    ul: '<div class="multiselect-container checkbox-list"></div>',
                    li: '<a class="multiselect-option text-dark text-decoration-none"></a>'
                }
            });
        });
    </script>
    <style type="text/css">

        #example-checkbox-list-container .checkbox-list > li > a {
            display: block;
            padding: 3px 0;
            clear: both;
            font-weight: normal;
            line-height: 1.42857143;
            color: #333;
            white-space: nowrap;
        }

        #example-checkbox-list-container .checkbox-list > li > a:hover,
        #example-checkbox-list-container .checkbox-list > li > a:focus {
            color: #333;
            text-decoration: none;
            background-color: transparent;
        }

        #example-checkbox-list-container .checkbox-list > .active > a,
        #example-checkbox-list-container .checkbox-list > .active > a:hover,
        #example-checkbox-list-container .checkbox-list > .active > a:focus {
            color: #333;
            text-decoration: none;
            background-color: transparent;
            outline: 0;
        }

        #example-checkbox-list-container .checkbox-list > .disabled > a,
        #example-checkbox-list-container .checkbox-list > .disabled > a:hover,
        #example-checkbox-list-container .checkbox-list > .disabled > a:focus {
            color: #777;
        }

        #example-checkbox-list-container .checkbox-list > .disabled > a:hover,
        #example-checkbox-list-container .checkbox-list > .disabled > a:focus {
            text-decoration: none;
            cursor: unset;
            background-color: transparent;
            background-image: none;
            filter: progid:DXImageTransform.Microsoft.gradient(enabled = false);
        }

        #example-checkbox-list-container .checkbox-list > li > a > label {
            padding: 3px 0 3px 20px;
        }

        @media (min-width: 768px) {
            #example-checkbox-list-container .checkbox-list > li {
                float: left;
                width: 33%;
            }
            #example-checkbox-list-container .checkbox-list-vertical > li {
                float: none;
                width: 100%;
            }
        }

        #example-checkbox-list-container .multiselect-container.checkbox-list {
            position: static;
        }

    </style>
    <div class="btn-group">
        <select id="example-checkbox-list" multiple="multiple">
            <option value="1">Option 1</option>
            <option value="2">Option 2</option>
            <option value="3">Option 3</option>
            <option value="4">Option 4</option>
            <option value="5">Option 5</option>
            <option value="6">Option 6</option>
        </select>
    </div>

## Server-Side Processing

The below example uses a PHP script to demonstrate Server-Side Processing. Therefore, the below example will not run online - download the repository and try it on a local server.

In order to receive the correct data after submitting the form, the used `select` has to have an appropriate name. Note that an `[]` needs to be appended to the name when using the `multiple` option/attribute. Per default, the checkboxes used within the multiselect will not be submitted, however, this can be changed by adapting `checkboxName`. The select all option as well as the text input used for the filter will not be submitted. As this may be useful, the name of the select all checkbox may be adapted using the `selectAllName` option. The value of the select all checkbox can be controlled by the `selectAllValue` option while the values of the remaining checkboxes correspond to the values used by the `option`'s of the original `select`.

The plugin naturally supports the `required` attribute.

Multiselect
Text Input
Checkbox
Radio 1
Radio 2

    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-post').multiselect({
                includeSelectAllOption: true,
                enableFiltering: true
            });
        });
    </script>
    <form class="form-horizontal" method="POST" action="post.php">
        <div class="form-group">
            <label class="col-sm-2 control-label">Multiselect</label>
            <div class="col-sm-10">
                <select id="example-post" name="multiselect[]" multiple="multiple">
                    <option value="1">Option 1</option>
                    <option value="2">Option 2</option>
                    <option value="3">Option 3</option>
                    <option value="4">Option 4</option>
                    <option value="5">Option 5</option>
                    <option value="6">Option 6</option>
                </select>
            </div>
        </div>
        <div class="form-group">
            <label class="col-sm-2 control-label">Text Input</label>
            <div class="col-sm-10">
                <input type="text" name="text" class="form-control" placeholder="Text Input" />
            </div>
        </div>
        <div class="form-group">
            <div class="col-sm-offset-2 col-sm-10">
                <div class="checkbox">
                    <label>
                        <input type="checkbox" name="checkbox"> Checkbox
                    </label>
                </div>
            </div>
        </div>
        <div class="form-group">
            <div class="col-sm-offset-2 col-sm-10">
                <div class="radio">
                    <label>
                        <input type="radio" name="radio"> Radio 1
                    </label>
                </div>
                <div class="radio">
                    <label>
                        <input type="radio" name="radio"> Radio 2
                    </label>
                </div>
            </div>
        </div>
        <div class="form-group">
            <div class="col-sm-offset-2 col-sm-10">
                <button type="submit" class="btn btn-default">Submit</button>
            </div>
        </div>
    </form>

The `checkboxName` option can also be used to assign different names to the `option's`, for example for different `optgroup`s.

Note that in the below example, `$_POST` will contain both the `multiselect` and the `group1` as well as `group2` keys.

Multiselect

    <script type="text/javascript">
        $(document).ready(function() {
            $('#example-post-checkboxName').multiselect({
                checkboxName: function(option) {
                    var $optgroup = $(option).closest('optgroup');
                    if ($optgroup.id == 'example-post-checkboxName-1') {
                        return 'group1[]';
                    }
                    else {
                        return 'group2[]';
                    }
                }
            });
        });
    </script>
    <form class="form-horizontal" method="POST" action="post.php">
        <div class="form-group">
            <label class="col-sm-2 control-label">Multiselect</label>
            <div class="col-sm-10">
                <select id="example-post-checkboxName" name="multiselect[]" multiple="multiple" required>
                    <optgroup label="Group 1" id="example-post-checkboxName-1">
                        <option value="1-1">Option 1.1</option>
                        <option value="1-2">Option 1.2</option>
                        <option value="1-3">Option 1.3</option>
                    </optgroup>
                    <optgroup label="Group 1" id="example-post-checkboxName-2">
                        <option value="2-1">Option 2.1</option>
                        <option value="2-2">Option 2.2</option>
                        <option value="2-3">Option 2.3</option>
                    </optgroup>
                </select>
            </div>
        </div>
        <div class="form-group">
            <div class="col-sm-offset-2 col-sm-10">
                <button type="submit" class="btn btn-default">Submit</button>
            </div>
        </div>
    </form>

## Keyboard Support

`Tab` | As with other form elements, `Tab` is used to switch to the next form elements. `Tab` can be used when the dropdown is opened as well as when it is closed.
`Enter` | `Enter` is used to open the dropdown and select options (for selecting options, `Space` can be used, as well). After a multiselect is in focus, pressing `Enter` will open the dropdown. Then, the options can be traversed using arrow up and down.
`Arrow Up/Arrow Down` | Used to traverse the options after opening the dropdown. An option can be selected using `Space` or `Enter`.

## Frequently Asked Questions

How to contribute?
  Pull requests to add additional feature or fix known bugs are always welcome! However, to make it easy for me to review and merge your pull request, the following guidelines should be considered:
  - Check the Issue Tracker and the FAQ before starting to implement a feature or fix.
  - Add one pull request per feature/fix. Otherwise, I cannot guarantee that I will merge the pull request.
  - Always document your changes. If new features are added, new options or methods should be added to the documentation (`index.html`) and appropriate examples should be added.
  - Add a thorough description to your pull request - yes, I am able to read your code, however, reading your description may speed things up!
  - Add comments to your code!
  A full list of contributors can be found here.
How about older browsers as for example Internet Explorer 6, 7 and 8?
  With version 2.0, jQuery no longer supports the older IE versions. Nevertheless, the plugin should run as expected using the 1.x branch of jQuery. See here for details.
May I use the plugin in a commercial project (e.g. a commercial Wordpress/Joomla theme)?
  The plugin is dual licensed under the Apache License v2.0 and the BSD 3-Clause License. The BSD 3-Clause License allows to use the plugin in commercial projects as long as all source files associated with this plugin retain the copyright notice.
Using `return false;` within the `onChange` option does not prevent the option from being selected/deselected ...
  The `return` statement within the `onChange` method has no influence on the result. For preventing an option from being deselected or selected have a look at the examples in the Further Examples section.
How to change the button class depending on the number of selected options?
  This issue is addressed in 332.
Why does the plugin crash when using `.multiselect('select', value);` or `.multiselect('deselect', value);`?
  This may be caused when the class used for the `select` occurs for other elements, as well. In addition this may be caused if the multiselect has the class `.multiselect`. See #330.
How to check whether filtering all options resulted no options being displayed (except the select all option)?
  This issue is discussed in #317.
How to use multiple plugin instances running single selections on one page?
  There is a minor bug when using multiple plugin instances with single selection on one page. The bug is described here: #331. A possible fix is suggested here: #336.
How to use the plugin within a `form.form-inline`?
  This issue is addressed in #322
Using jQuery, how to get the selected options dynamically?

      //  get all option elements
      $('#example option:selected');

      //  get all option element values
      $('#example option:selected').map(function(a, item){return item.value;});

How to get the selected options using PHP?
  This issue is addressed here: https://github.com/davidstutz/bootstrap-multiselect/issues/323. Mainly there are two ways, either add a name to the `select`:

      <select id="example2" multiple="multiple" name="select[]"></select>

  Or add an appropriate name to the checkboxes:

      $('#example2').multiselect({
          checkboxName: function(option) {
              return 'multiselect[]';
          }
      });

Why does the plugin not work in Chrome for Mobile?
  This may be caused by several reasons one of which is described and resolved here: #223.
How to underline the searched text when using the filter?
  This issue is discussed in #309.
How to hide the checkboxes?
  A related issue is discussed in #205 and includes a possible solution when using CSS to hide the checkboxes:

      .multiselect-container input {
          display: none
      }

How to use Bootstrap Multiselect using `$.validate`?
  This topic is discussed in issue #347. The fix suggested is as follows:

      var $form = $("#myForm");
      var validator = $form.data('validator');
      validator.settings.ignore = ':hidden:not(".multiselect")';

How to prevent the plugin from selecting the first option in single select mode?
  This issue is mainly due to the default behavior of most browsers. A workaround can be found here: #129.
Which are the minimum required components of Twitter Botostrap to get the plugin working?
  The plugin needs at least the styles for forms and dropdowns. In addition the JavaScript dropdown plugin from Twitter Bootstrap is required. Details can be found here: #344.
How to use the `.multiselect('dataprovider', data)` method?
  Have a look at the Methods section. In the past, there has been some confusion about how the method handles option groups. If the documentation does not help you, have a look at the issue tracker, as for example issue #356.
A `type="reset"` button does not refresh the multiselect, what to do?
  Have a look at the Further Examples section (in addition, issue 360 discussed this).
Using multiple `select`'s in single selection mode with `option`'s sharing values across the different `select`'s.
  This issue is discussed in detail here: #362. A simple solution is to use different option values for the option `checkboxName`:

      $('.multiselect').multiselect({
          checkboxName: function(option) {
              return _.uniqueId('multiselect_');
          }
      });

  where `_.uniqueId('multiselect_')` should be replaced with a random generator. Alternatively, a unique value for `checkboxName` can be used for each multiselect.
How to avoid `TypeError: Cannot read property "toString" of ...`?
  This error may be thrown if `null` or `undefined` is provided as argument of `.multiselect('select', value)` or `.multiselect('deselect', value)`, see #386.
Why is there no "uncheck all" option?
  This issue is discussed in #271.
Esc does not close the dropdown?!
  This issue is discussed in #368. Currently, pressing `Esc` will not close the dropdown as there were some bugs with this.
How to keep the dropdown open?
  This issue is discussed here: #426.
Why is the dropdown not showing (or only partly shown) within modals?
  This is a general issue not directly related to Bootstrap Multiselect: #455.
How do add icons to the options (#475)?
  Adapt the `optionLabel` option as follows:

      optionLabel: function(element){
          return $(element).attr('label') || $(element).html();
      },

How to add a deselect all functionality (the inverse to the select all option)?
  This issue was discussed in the following pull request: #487.
How to bind object values using Knockout JS?

  This issue was discussed in #532.

  The plugin depends upon the following standard knockout bindings: `options`, `value`, `selectedOptions`, `enable`, `disable`. When these options change, they will update the internal `select` element and `.multiselect('refresh')` is triggered.

  - `options`: when `options` is an observable and changes, the `option`'s inside the `select` are updated by knockout and the plugin refreshes.
  - `value`: can only be used in single selection mode; Knockout does not support using the value binding handler to update a `select` with `multiple="multiple"`.
  - `selectedOptions`: this is a standard knockout binding that updates the checked options inside the `select` element; use with `multiple="multiple"`.
  - `enable`: enable the plugin.
  - `disable`: disable the plugin.

  Any other options inside the multiselect data bind are passed to the jQuery multiselect plugin.

Options do net get updated when using Angular JS?
  This issues was discussed in #519.
Is there a search event?
  This was discussed here: #530.
How to use the plugin with a local jQuery variable?
  This was discussed (and solved) here: #686
how to use font-awesome for checkboxes?
  This issue was discussed here: #576
How to focus on search/fiter input on dropdown open?
  This issue is discussed in #615 and #153.
How to initialize the plugin in npm?
  This issue is discussed here: #585. The proposed workaround looks as follows:

      var $ = require('jquery');
      var multiselect = require('bootstrap-multiselect');
      $.multiselect = multiselect;

      $("#example").multiselect();

How to show the dropdown on hover?
  This can be achieved using a bit of CSS, see this StackOverflow discussion.
Can I use Font Awesome instead of Bootstrap's glyphicons?
  Yes, see here: #887.

## Known Issues

See the Issue Tracker.

## Migrating to Bootstrap v4

For migrating your project to Bootstrap v4 follow the instructions from Bootstrap. Breaking changes for the bootstrap-multiselect are described in the following section:

### Templates

In Bootstrap v4 Dropdown menus are no longer created with `ul`s and `li`s but with `div`s and `a`s. The Dropdown of the multiselect was changed to work in the same way like it is recommended by Bootstrap. To make template names indepedent of the concrete HTML structure they were also adapted:

- The template `ul` was renamed to `popupContainer`
- The template `li` was renamed to `option`
- The template `liGroup` was renamed to `optionGroup`

### Fonts

Bootstrap dropped the Glyphicons icon font therefore the icons in the multiselect where changed to Font Awesome. To get the icons working you need to download Font Awesome and include the all.css or all.min.css into your project. If you change the location of the font files you may need to also adapt the paths at the end of all.css and all.min.css.

## License

Apache License, Version 2.0

  Copyright 2012 - 2020 David Stutz

  Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0.

  Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

BSD 3-Clause License

  Copyright (c) 2012 - 2020 David Stutz

  All rights reserved.

  Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

  - Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
  - Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
  - Neither the name of David Stutz nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

© 2012 - 2020 David Stutz, Impressum, Datenschutz - dual licensed: Apache License v2.0, BSD 3-Clause License