jQuery bootstrapSelect Plugin:

In this article, we will understand the jQuery bootstrap select plugin in detail. Bootstrap select plugin is used to select the options from the drop-down option.

Following are the various examples of jQuery bootstrap select plugin.

Example 1:

<!DOCTYPE html>
<html>
<head>
	<meta charset = "utf-8">
	<meta http-equiv = "x-ua-compatible" content="ie=edge">

	<title> jQuery Bootstrap Dropdown Plugin </title>

	<meta name = "description" content = " ">
	<meta name = "viewport"
		content="width=device-width, initial-scale=1">
	
	<link rel = ?stylesheet" href =
"https://fonts.googleapis.com/css?family=Roboto:300,500">
	<link rel = "stylesheet" href = "
https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css"
			integrity =
"sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u"
			crossorigin = "anonymous">
	<link rel = "stylesheet" href = "
https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap-theme.min.css"
			integrity =
"sha384-rHyoN1iRsVXV4nD0JutlnGaslCJuC7uwjduW9SVrLvRYooPp2bWYgmgJQIXwl/Sp"
			crossorigin = "anonymous">
	<link rel = "stylesheet" href = "bootstrapSelect.css">
	<style>
	h2 {
  position: relative;
  font-family: "Raleway", sans-serif;
  font-weight: 300;
  font-size: 40px;
  color: #080808;
  -webkit-transition: all 0.4s ease 0s;
  -o-transition: all 0.4s ease 0s;
  transition: all 0.4s ease 0s;
  text-align: center;
}

		body
		{
			font-family: Helvetica, Arial, sans-serif;
		}
		#containerID
	{
			width: 90%;
			padding-top: 20px;
			padding-left: 20px;					
		}	
		.science {
			color: #0099aa;
		}
		.maths {
			color: #00aaaa;
		}
		.computers {
			color: #aa9900;
		}
		.literature {
			color: #2a00aa;
			font-weight: bold;
			text-decoration: underline;
		}
	</style>
</head>
<body>
<h2> jQuery Bootstrap Dropdown Plugin Example </h2>
	<div id = "containerID">
		<div id = "bootstrapSelectZone"
			style = "max-width:600px; width:600px;">
		<div>
				<label> What is your favourite subject? </label> <br />
				<select id = "selectOptionID">
					<option value = " "> </option>
					<option class = "science" value =  "science">
					Science
					</option>
					<option class = "maths" value = "maths"
							selected = "selected">
					Maths
					</option>
					<option class = "computers" value = "computers">
					Computers
					</option>
					<option class =
"literature" value = "literature">
					Literature
					</option>
					<option value = "history"> History  </option>
				</select>
			</div>
			<br />
		</div>
	<script src = "
https://cdnjs.cloudflare.com/ajax/libs/modernizr/2.8.3/modernizr.min.js">
	</script>
	<script src = "
https://code.jquery.com/jquery-2.2.4.min.js"
			integrity=
"sha256-BbhdlvQf/xTY9gja0Dq3HiwQF8LaCRTXxZKRutelT44="
			crossorigin = "anonymous">
	</script>
	<script src = "
https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"
			integrity=
"sha384-Tc5IQib027qvyjSMfHjOMaLkfuWVxZxUPnCJA7l2mCWNIpG9mGCD8wGNIcPD7Txa"
			crossorigin = "anonymous">
	</script>
	<script src = "bootstrapSelect.js"> </script>

		<script>
			$(document).ready(function () {
				
				$("#btnSetID").hide();
				$("#btnEmptyID").hide();			

				$("#btnBootstrapID").on("click", function () {
					$("#selectOptionID").bootstrapSelect
					("init", { "maxWidth": 500 });
			$("#btnBootstrapID").hide();
					$("#btnSetID").show();
					$("#btnEmptyID").show();				
				});

				$("#btnEmptyID").on("click", function () {
					$("#selectOptionID").bootstrapSelect("empty");
				});

				$("#btnSetID").on("click", function () {
					$("#selectOptionID").bootstrapSelect
				("setValue", "literature");
				});			
				
			});
		</script>
	</div>
</html>

Explanation:

In the above example, we created an example of jQuery bootstrap select plugin with single option selection. In this we can select only single value from dropdown list.

Output:

Following is the output of this example.

Example 2:

<!DOCTYPE html>
<html>
<head>
	<meta charset = "utf-8">
	<meta http-equiv = "x-ua-compatible" content="ie=edge">

	<title> jQuery Bootstrap Dropdown Plugin </title>

	<meta name = "description" content = " ">
	<meta name = "viewport"
		content="width=device-width, initial-scale=1">
	
	<link rel = ?stylesheet" href =
"https://fonts.googleapis.com/css?family=Roboto:300,500">
	<link rel = "stylesheet" href = "
https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css"
			integrity =
"sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u"
			crossorigin = "anonymous">
	<link rel = "stylesheet" href = "
https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap-theme.min.css"
			integrity =
"sha384-rHyoN1iRsVXV4nD0JutlnGaslCJuC7uwjduW9SVrLvRYooPp2bWYgmgJQIXwl/Sp"
			crossorigin = "anonymous">
	<link rel = "stylesheet" href = "bootstrapSelect.css">
	<style>
	h2 {
  position: relative;
  font-family: "Raleway", sans-serif;
  font-weight: 300;
  font-size: 40px;
  color: #080808;
  -webkit-transition: all 0.4s ease 0s;
  -o-transition: all 0.4s ease 0s;
  transition: all 0.4s ease 0s;
  text-align: center;
}

.multiselect-container{position:absolute;list-style-type:none;margin:0;padding:0}
.multiselect-container .input-group{margin:5px}.multiselect-container>li{padding:0}
.multiselect-container>li>a.multiselect-all label{font-weight:700}
.multiselect-container>li.multiselect-group label{margin:0;padding:3px 20px 3px 20px;height:100%;font-weight:700}
.multiselect-container>li.multiselect-group-clickable label{cursor:pointer}
.multiselect-container>li>a{padding:0}
.multiselect-container>li>a>label{margin:0;height:100%;cursor:pointer;font-weight:400;padding:3px 20px 3px 40px}
.multiselect-container>li>a>label.radio,.multiselect-container>li>a>label.checkbox{margin:0}
.multiselect-container>li>a>label>input[type=checkbox]{margin-bottom:5px}.btn-group>.btn-group:nth-child(2)>
.multiselect.btn{border-top-left-radius:4px;border-bottom-left-radius:4px}
.form-inline .multiselect-container label.checkbox,.form-inline .multiselect-container label.radio{
padding:3px 20px 3px 40px}.form-inline .multiselect-container li a label.checkbox input[type=checkbox],
.form-inline .multiselect-container li a label.radio input[type=radio]{margin-left:-20px;margin-right:0}

.multiselect-group input {
  display: none;
}
li.multiselect-group a {
  padding-left: 20px !important;
}

	</style>
</head>
<body>
<h1> Example </h1>
<h2> jQuery Bootstrap Dropdown Plugin Example </h2>
	<select id="example-multiple-optgroups" multiple="multiple">
  <optgroup 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 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>

	<script src = "
https://cdnjs.cloudflare.com/ajax/libs/bootstrap-multiselect/0.9.13/js/bootstrap-multiselect.min.js"
			integrity=
"sha256-BbhdlvQf/xTY9gja0Dq3HiwQF8LaCRTXxZKRutelT44="
			crossorigin = "anonymous">
	</script>
	<script src = "
https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"
			integrity=
"sha384-Tc5IQib027qvyjSMfHjOMaLkfuWVxZxUPnCJA7l2mCWNIpG9mGCD8wGNIcPD7Txa"
			crossorigin = "anonymous">
	</script>
	<script src = "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.2.1/jquery.min.js"> </script>

		<script>
!function ($) {
    "use strict";
    if (typeof ko !== 'undefined' && ko.bindingHandlers && !ko.bindingHandlers.multiselect) {
        ko.bindingHandlers.multiselect = {
            after: ['options', 'value', 'selectedOptions', 'enable', 'disable'],

            init: function(element, valueAccessor, allBindings, viewModel, bindingContext) {
                var $element = $(element);
                var config = ko.toJS(valueAccessor());
                $element.multiselect(config);
                if (allBindings.has('options')) {
                    var options = allBindings.get('options');
                    if (ko.isObservable(options)) {
                        ko.computed({
                            read: function() {
                                options();
                                setTimeout(function() {
                                    var ms = $element.data('multiselect');
                                    if (ms)
                                        ms.updateOriginalOptions();//Not sure how beneficial this is.
                                    $element.multiselect('rebuild');
                                }, 1);
                            },
                            disposeWhenNodeIsRemoved: element
                        });
                    }
                }
                if (allBindings.has('value')) {
                    var value = allBindings.get('value');
                    if (ko.isObservable(value)) {
                        ko.computed({
                            read: function() {
                                value();
                                setTimeout(function() {
                                    $element.multiselect('refresh');
                                }, 1);
                            },
                            disposeWhenNodeIsRemoved: element
                        }).extend({ rateLimit: 100, notifyWhenChangesStop: true });
                    }
                }
                if (allBindings.has('selectedOptions')) {
                    var selectedOptions = allBindings.get('selectedOptions');
                    if (ko.isObservable(selectedOptions)) {
                        ko.computed({
                            read: function() {
                                selectedOptions();
                                setTimeout(function() {
                                    $element.multiselect('refresh');
                                }, 1);
                            },
                            disposeWhenNodeIsRemoved: element
                        }).extend({ rateLimit: 100, notifyWhenChangesStop: true });
                    }
                }

                var setEnabled = function (enable) {
                    setTimeout(function () {
                        if (enable)
                            $element.multiselect('enable');
                        else
                            $element.multiselect('disable');
                    });
                };

                if (allBindings.has('enable')) {
                    var enable = allBindings.get('enable');
                    if (ko.isObservable(enable)) {
                        ko.computed({
                            read: function () {
                                setEnabled(enable());
                            },
                            disposeWhenNodeIsRemoved: element
                        }).extend({ rateLimit: 100, notifyWhenChangesStop: true });
                    } else {
                        setEnabled(enable);
                    }
                }

                if (allBindings.has('disable')) {
                    var disable = allBindings.get('disable');
                    if (ko.isObservable(disable)) {
                        ko.computed({
                            read: function () {
                                setEnabled(!disable());
                            },
                            disposeWhenNodeIsRemoved: element
                        }).extend({ rateLimit: 100, notifyWhenChangesStop: true });
                    } else {
                        setEnabled(!disable);
                    }
                }

                ko.utils.domNodeDisposal.addDisposeCallback(element, function() {
                    $element.multiselect('destroy');
                });
            },

            update: function(element, valueAccessor, allBindings, viewModel, bindingContext) {
                var $element = $(element);
                var config = ko.toJS(valueAccessor());

                $element.multiselect('setOptions', config);
                $element.multiselect('rebuild');
            }
        };
    }

    function forEach(array, callback) {
        for (var index = 0; index < array.length; ++index) {
            callback(array[index], index);
        }
    }
    function Multiselect(select, options) {
        this.$select = $(select);
        if (this.$select.attr("data-placeholder")) {
            options.nonSelectedText = this.$select.data("placeholder");
        }
        
        this.options = this.mergeOptions($.extend({}, options, this.$select.data()));
        
        this.originalOptions = this.$select.clone()[0].options;
        this.query = '';
        this.searchTimeout = null;
        this.lastToggledInput = null;

        this.options.multiple = this.$select.attr('multiple') === "multiple";
        this.options.onChange = $.proxy(this.options.onChange, this);
        this.options.onDropdownShow = $.proxy(this.options.onDropdownShow, this);
        this.options.onDropdownHide = $.proxy(this.options.onDropdownHide, this);
        this.options.onDropdownShown = $.proxy(this.options.onDropdownShown, this);
        this.options.onDropdownHidden = $.proxy(this.options.onDropdownHidden, this);
        this.options.onInitialized = $.proxy(this.options.onInitialized, this);
                this.buildContainer();
        this.buildButton();
        this.buildDropdown();
        this.buildSelectAll();
        this.buildDropdownOptions();
        this.buildFilter();

        this.updateButtonText();
        this.updateSelectAll(true);

        if (this.options.disableIfEmpty && $('option', this.$select).length <= 0) {
            this.disable();
        }
        
        this.$select.hide().after(this.$container);
        this.options.onInitialized(this.$select, this.$container);
    }

    Multiselect.prototype = {

        defaults: {
            
            buttonText: function(options, select) {
                if (options.length === 0) {
                    return this.nonSelectedText;
                }
                else if (this.allSelectedText 
                            && options.length === $('option', $(select)).length 
                            && $('option', $(select)).length !== 1 
                            && this.multiple) {

                    if (this.selectAllNumber) {
                        return this.allSelectedText + ' (' + options.length + ')';
                    }
                    else {
                        return this.allSelectedText;
                    }
                }
                else if (options.length > this.numberDisplayed) {
                    return options.length + ' ' + this.nSelectedText;
                }
                else {
                    var selected = '';
                    var delimiter = this.delimiterText;
                    
                    options.each(function() {
                        var label = ($(this).attr('label') !== undefined) ? $(this).attr('label') : $(this).text();
                        selected += label + delimiter;
                    });
                    
                    return selected.substr(0, selected.length - 2);
                }
            },
            
            buttonTitle: function(options, select) {
                if (options.length === 0) {
                    return this.nonSelectedText;
                }
                else {
                    var selected = '';
                    var delimiter = this.delimiterText;
                    
                    options.each(function () {
                        var label = ($(this).attr('label') !== undefined) ? $(this).attr('label') : $(this).text();
                        selected += label + delimiter;
                    });
                    return selected.substr(0, selected.length - 2);
                }
            },
            
            optionLabel: function(element){
                return $(element).attr('label') || $(element).text();
            },
            
            onDropdownShow: function(event) {

            },
            
            onDropdownHide: function(event) {

            },
            onDropdownShown: function(event) {
                
            },
            
            onDropdownHidden: function(event) {
                
            },
            
            onInitialized: function($select, $container) {

            },
            enableHTML: false,
            buttonClass: 'btn btn-default',
            inheritClass: false,
            buttonWidth: 'auto',
            buttonContainer: '<div class="btn-group" />',
            dropRight: false,
            selectedClass: 'active',
            
            maxHeight: false,
            checkboxName: false,
            includeSelectAllOption: false,
            includeSelectAllIfMoreThan: 0,
            selectAllText: ' Select all',
            selectAllValue: 'multiselect-all',
            selectAllName: false,
            selectAllNumber: true,
            selectAllJustVisible: true,
            enableFiltering: false,
            enableCaseInsensitiveFiltering: false,
            enableFullValueFiltering: false,
            enableClickableOptGroups: false,
            filterPlaceholder: 'Search',
            filterBehavior: 'text',
            includeFilterClearBtn: true,
            preventInputChangeEvent: false,
            nonSelectedText: 'None selected',
            nSelectedText: 'selected',
            allSelectedText: 'All selected',
            numberDisplayed: 3,
            disableIfEmpty: false,
            delimiterText: ', ',
            templates: {
                button: '<button type="button" class="multiselect dropdown-toggle" data-toggle="dropdown"><span class="multiselect-selected-text"></span> <b class="caret"></b></button>',
                ul: '<ul class="multiselect-container dropdown-menu"></ul>',
                filterClearBtn: '<span class="input-group-btn"><button class="btn btn-default multiselect-clear-filter" type="button"><i class="glyphicon glyphicon-remove-circle"></i></button></span>',
                li: '<li><a tabindex="0"><label></label></a></li>',
                divider: '<li class="multiselect-item divider"></li>',
                liGroup: '<li class="multiselect-item multiselect-group"><label></label></li>'
            }
        },

        constructor: Multiselect,
        buildContainer: function() {
            this.$container = $(this.options.buttonContainer);
            this.$container.on('show.bs.dropdown', this.options.onDropdownShow);
            this.$container.on('hide.bs.dropdown', this.options.onDropdownHide);
            this.$container.on('shown.bs.dropdown', this.options.onDropdownShown);
            this.$container.on('hidden.bs.dropdown', this.options.onDropdownHidden);
        },        buildButton: function() {
            this.$button = $(this.options.templates.button).addClass(this.options.buttonClass);
            if (this.$select.attr('class') && this.options.inheritClass) {
                this.$button.addClass(this.$select.attr('class'));
            }
           
            if (this.$select.prop('disabled')) {
                this.disable();
            }
            else {
                this.enable();
            }

            if (this.options.buttonWidth && this.options.buttonWidth !== 'auto') {
                this.$button.css({
                    'width' : this.options.buttonWidth,
                    'overflow' : 'hidden',
                    'text-overflow' : 'ellipsis'
                });
                this.$container.css({
                    'width': this.options.buttonWidth
                });
            }

        
            var tabindex = this.$select.attr('tabindex');
            if (tabindex) {
                this.$button.attr('tabindex', tabindex);
            }

            this.$container.prepend(this.$button);
        },

        
        buildDropdown: function() {

            this.$ul = $(this.options.templates.ul);

            if (this.options.dropRight) {
                this.$ul.addClass('pull-right');
            }

            if (this.options.maxHeight) {
                this.$ul.css({
                    'max-height': this.options.maxHeight + 'px',
                    'overflow-y': 'auto',
                    'overflow-x': 'hidden'
                });
            }

            this.$container.append(this.$ul);
        },

        buildDropdownOptions: function() {

            this.$select.children().each($.proxy(function(index, element) {

                var $element = $(element);
                
                var tag = $element.prop('tagName')
                    .toLowerCase();
            
                if ($element.prop('value') === this.options.selectAllValue) {
                    return;
                }

                if (tag === 'optgroup') {
                    this.createOptgroup(element);
                }
                else if (tag === 'option') {

                    if ($element.data('role') === 'divider') {
                        this.createDivider();
                    }
                    else {
                        this.createOptionValue(element);
                    }

                }

                
            }, this));

            $('li input', this.$ul).on('change', $.proxy(function(event) {
                var $target = $(event.target);

                var checked = $target.prop('checked') || false;
                var isSelectAllOption = $target.val() === this.options.selectAllValue;
                if (this.options.selectedClass) {
                    if (checked) {
                        $target.closest('li')
                            .addClass(this.options.selectedClass);
                    }
                    else {
                        $target.closest('li')
                            .removeClass(this.options.selectedClass);
                    }
                }

                var value = $target.val();
                var $option = this.getOptionByValue(value);

                var $optionsNotThis = $('option', this.$select).not($option);
                var $checkboxesNotThis = $('input', this.$container).not($target);

                if (isSelectAllOption) {
                    if (checked) {
                        this.selectAll(this.options.selectAllJustVisible);
                    }
                    else {
                        this.deselectAll(this.options.selectAllJustVisible);
                    }
                }

                if(!isSelectAllOption){
                    if (checked) {
                        $option.prop('selected', true);

                        if (this.options.multiple) {
                            $option.prop('selected', true);
                        }
                        else {
                            if (this.options.selectedClass) {
                                $($checkboxesNotThis).closest('li').removeClass(this.options.selectedClass);
                            }

                            $($checkboxesNotThis).prop('checked', false);
                            $optionsNotThis.prop('selected', false);
                            this.$button.click();
                        }

                        if (this.options.selectedClass === "active") {
                            $optionsNotThis.closest("a").css("outline", "");
                        }
                    }
                    else {
                        
                        $option.prop('selected', false);
                    }
                }

                this.$select.change();

                this.updateButtonText();
                this.updateSelectAll();

                this.options.onChange($option, checked);

                if(this.options.preventInputChangeEvent) {
                    return false;
                }
            }, this));

            $('li a', this.$ul).on('mousedown', function(e) {
                if (e.shiftKey) {

                    return false;
                }
            });
        
            $('li a', this.$ul).on('touchstart click', $.proxy(function(event) {
                event.stopPropagation();

                var $target = $(event.target);
                
                if (event.shiftKey && this.options.multiple) {
                    if($target.is("label")){ 
                        event.preventDefault();
                        $target = $target.find("input");
                        $target.prop("checked", !$target.prop("checked"));
                    }
                    var checked = $target.prop('checked') || false;

                    if (this.lastToggledInput !== null && this.lastToggledInput !== $target) { // Make sure we actually have a range
                        var from = $target.closest("li").index();
                        var to = this.lastToggledInput.closest("li").index();
                        
                        if (from > to) { // Swap the indices
                            var tmp = to;
                            to = from;
                            from = tmp;
                        }
                                                var range = this.$ul.find("li").slice(from, to).find("input");
                        
                        range.prop('checked', checked);
                        
                        if (this.options.selectedClass) {
                            range.closest('li')
                                .toggleClass(this.options.selectedClass, checked);
                        }
                        
                        for (var i = 0, j = range.length; i < j; i++) {
                            var $checkbox = $(range[i]);

                            var $option = this.getOptionByValue($checkbox.val());

                            $option.prop('selected', checked);
                        }                   
                    }
                    
                    
                    $target.trigger("change");
                }
                
                if($target.is("input") && !$target.closest("li").is(".multiselect-item")){
                    this.lastToggledInput = $target;
                }

                $target.blur();
            }, this))

                if (event.keyCode === 9 && this.$container.hasClass('open')) {
                    this.$button.click();
                }
                else {
                    var $items = $(this.$container).find("li:not(.divider):not(.disabled) a").filter(":visible");

                    if (!$items.length) {
                        return;
                    }
                  var $current = $items.eq(index);
                    $current.focus();

                    if (event.keyCode === 32 || event.keyCode === 13) {
                        var $checkbox = $current.find('input');

                        $checkbox.prop("checked", !$checkbox.prop("checked"));
                        $checkbox.change();
                    }

                    event.stopPropagation();
                    event.preventDefault();
                }
            }, this));

            if(this.options.enableClickableOptGroups && this.options.multiple) {
                $('li.multiselect-group', this.$ul).on('click', $.proxy(function(event) {
                    event.stopPropagation();
                    var group = $(event.target).parent()                    var $options = group.nextUntil('li.multiselect-group');
                    var $visibleOptions = $options.filter(":visible:not(.disabled)");
                    var allChecked = true;
                    var optionInputs = $visibleOptions.find('input');
                    optionInputs.each(function() {
                        allChecked = allChecked && $(this).prop('checked');
                    });

                    optionInputs.prop('checked', !allChecked).trigger('change');
               }, this));
            }
        },

        createOptionValue: function(element) {
            var $element = $(element);
            if ($element.is(':selected')) {
                $element.prop('selected', true);
            }
            var label = this.options.optionLabel(element);
            var value = $element.val();
            var inputType = this.options.multiple ? "checkbox" : "radio";

            var $li = $(this.options.templates.li);
            var $label = $('label', $li);
            $label.addClass(inputType);
            $li.addClass(classes);

            if (this.options.enableHTML) {
                $label.html(" " + label);
            }
            else {
                $label.text(" " + label);
            }
        
            var $checkbox = $('<input/>').attr('type', inputType);

            if (this.options.checkboxName) {
                $checkbox.attr('name', this.options.checkboxName);
            }
            $label.prepend($checkbox);

            var selected = $element.prop('selected') || false;
            $checkbox.val(value);

            if (value === this.options.selectAllValue) {
                $li.addClass("multiselect-item multiselect-all");
                $checkbox.parent().parent()
                    .addClass('multiselect-all');
            }

            $label.attr('title', $element.attr('title'));

            this.$ul.append($li);

            if ($element.is(':disabled')) {
                $checkbox.attr('disabled', 'disabled')
                    .prop('disabled', true)
                    .closest('a')
                    .attr("tabindex", "-1")
                    .closest('li')
                    .addClass('disabled');
            }

            $checkbox.prop('checked', selected);

            if (selected && this.options.selectedClass) {
                $checkbox.closest('li')
                    .addClass(this.options.selectedClass);
            }
        },

            var $li = $(this.options.templates.liGroup);
            
            if (this.options.enableHTML) {
                $('label', $li).html(groupName);
            }
            else {
                $('label', $li).text(groupName);
            }
            
            if (this.options.enableClickableOptGroups) {
                $li.addClass('multiselect-group-clickable');
            }

            this.$ul.append($li);
            if ($(group).is(':disabled')) {
                $li.addClass('disabled');
            }
            $('option', group).each($.proxy(function(index, element) {
                this.createOptionValue(element);
            }, this));
        },

        
        buildSelectAll: function() {
            if (typeof this.options.selectAllValue === 'number') {
                this.options.selectAllValue = this.options.selectAllValue.toString();
            }
            
                if (this.options.includeSelectAllDivider) {
                    this.$ul.prepend($(this.options.templates.divider));
                }

                var $li = $(this.options.templates.li);
                $('label', $li).addClass("checkbox");
                
                if (this.options.enableHTML) {
                    $('label', $li).html(" " + this.options.selectAllText);
                }
                else {
                    $('label', $li).text(" " + this.options.selectAllText);
                }
                
                if (this.options.selectAllName) {
                    $('label', $li).prepend('<input type="checkbox" name="' + this.options.selectAllName + '" />');
                }
                else {
                    $('label', $li).prepend('<input type="checkbox" />');
                }
                
                var $checkbox = $('input', $li);
                $checkbox.val(this.options.selectAllValue);

                $li.addClass("multiselect-item multiselect-all");
                $checkbox.parent().parent()
                    .addClass('multiselect-all');

                this.$ul.prepend($li);

                $checkbox.prop('checked', false);
            }
        },

        
        destroy: function() {
            this.$container.remove();
            this.$select.show();
            this.$select.data('multiselect', null);
        },

        refresh: function () {
            var inputs = $.map($('li input', this.$ul), $);
            
            $('option', this.$select).each($.proxy(function (index, element) {
                var $elem = $(element);
                var value = $elem.val();
                var $input;
                for (var i = inputs.length; 0 < i--; /**/) {
                    if (value !== ($input = inputs[i]).val())
                        continue; // wrong li

                    if ($elem.is(':selected')) {
                        $input.prop('checked', true);

                        if (this.options.selectedClass) {
                            $input.closest('li')
                                .addClass(this.options.selectedClass);
                        }
                    }
                    else {
                        $input.prop('checked', false);

                        if (this.options.selectedClass) {
                            $input.closest('li')
                                .removeClass(this.options.selectedClass);
                        }
                    }

                    if ($elem.is(":disabled")) {
                        $input.attr('disabled', 'disabled')
                            .prop('disabled', true)
                            .closest('li')
                            .addClass('disabled');
                    }
                    else {
                        $input.prop('disabled', false)
                            .closest('li')
                            .removeClass('disabled');
                    }
                    break; 
                }
            }, this));

            this.updateButtonText();
            this.updateSelectAll();
        },

        select: function(selectValues, triggerOnChange) {
            if(!$.isArray(selectValues)) {
                selectValues = [selectValues];
            }

            for (var i = 0; i < selectValues.length; i++) {
                var value = selectValues[i];

                if (value === null || value === undefined) {
                    continue;
                }

                var $option = this.getOptionByValue(value);
                var $checkbox = this.getInputByValue(value);

                if($option === undefined || $checkbox === undefined) {
                    continue;
                }
                
                if (!this.options.multiple) {
                    this.deselectAll(false);
                }
                
                if (this.options.selectedClass) {
                    $checkbox.closest('li')
                        .addClass(this.options.selectedClass);
                }

                $checkbox.prop('checked', true);
                $option.prop('selected', true);
                
                if (triggerOnChange) {
                    this.options.onChange($option, true);
                }
            }

            this.updateButtonText();
            this.updateSelectAll();
        },

            for (var i = 0; i < deselectValues.length; i++) {
                var value = deselectValues[i];

                if (value === null || value === undefined) {
                    continue;
                }

                var $option = this.getOptionByValue(value);
                var $checkbox = this.getInputByValue(value);

                if($option === undefined || $checkbox === undefined) {
                    continue;
                }

                if (this.options.selectedClass) {
                    $checkbox.closest('li')
                        .removeClass(this.options.selectedClass);
                }

                $checkbox.prop('checked', false);
                $option.prop('selected', false);
            }

            this.updateButtonText();
            this.updateSelectAll();
        },
        
                if ($.isArray(option.children)) { 
                    groupCounter++;
                    
                    $tag = $('<optgroup/>').attr({
                        label: option.label || 'Group ' + groupCounter,
                        disabled: !!option.disabled
                    });
                    
                    forEach(option.children, function(subOption) { 
                        $tag.append($('<option/>').attr({
                            value: subOption.value,
                            label: subOption.label || subOption.value,
                            title: subOption.title,
                            selected: !!subOption.selected,
                            disabled: !!subOption.disabled
                        }));
                    });
                }
                else {
                    $tag = $('<option/>').attr({
                        value: option.value,
                        label: option.label || option.value,
                        title: option.title,
                        class: option.class,
                        selected: !!option.selected,
                        disabled: !!option.disabled
                    });
                    $tag.text(option.label || option.value);
                }
                
                $select.append($tag);
            });
            
            this.rebuild();
        },

        
        enable: function() {
            this.$select.prop('disabled', false);
            this.$button.prop('disabled', false)
                .removeClass('disabled');
        },
        updateButtonText: function() {
            var options = this.getSelected();     
            if (this.options.enableHTML) {
                $('.multiselect .multiselect-selected-text', this.$container).html(this.options.buttonText(options, this.$select));
            }
            else {
                $('.multiselect .multiselect-selected-text', this.$container).text(this.options.buttonText(options, this.$select));
            }
            $('.multiselect', this.$container).attr('title', this.options.buttonTitle(options, this.$select));
        },

    $.fn.multiselect = function(option, parameter, extraOptions) {
        return this.each(function() {
            var data = $(this).data('multiselect');
            var options = typeof option === 'object' && option;
            if (!data) {
                data = new Multiselect(this, options);
                $(this).data('multiselect', data);
            }
            if (typeof option === 'string') {
                data[option](parameter, extraOptions);
                
                if (option === 'destroy') {
                    $(this).data('multiselect', false);
                }
            }
        });
    };

}(window.jQuery);

! function(e) {
	"use strict";
	jQuery.fn.multiselect.Constructor.prototype.selectAll = (function() {
		var cached_function	= jQuery.fn.multiselect.Constructor.prototype.selectAll;

		return function() {
			var args = Array.prototype.slice.call( arguments );
				args[0]= (this.options.enableCollapsibleOptGroups && this.options.multiple) ? false : args[0];
			cached_function.apply(this, args);
		};
	}());

	jQuery.fn.multiselect.Constructor.prototype.deselectAll = (function() {
		var cached_function	= jQuery.fn.multiselect.Constructor.prototype.deselectAll;

		return function() {
			var args= Array.prototype.slice.call( arguments );
				args[0]= (this.options.enableCollapsibleOptGroups && this.options.multiple) ? false : args[0];
			cached_function.apply(this, args);
		};
	}());

	jQuery.fn.multiselect.Constructor.prototype.createOptgroup = (function() {
		var cached_function	= jQuery.fn.multiselect.Constructor.prototype.createOptgroup;

		return function() {
			var args	= Array.prototype.slice.call( arguments );
			var t		= args[0];
			if (this.options.enableCollapsibleOptGroups && this.options.multiple) {
				var n = e(t).attr("label");
				var v = e(t).attr("value");
				var r = e('<li class="multiselect-item multiselect-group"><a href="javascript:void(0);"><input type="checkbox" value="' + v + '"/><b> ' + n + '<b class="caret"></b></b></a></li>');

				if (this.options.enableClickableOptGroups) {
					r.addClass("multiselect-group-clickable")
				}
				this.$ul.append(r);
				if (e(t).is(":disabled")) {
					r.addClass("disabled")
				}
				e("option", t).each(e.proxy(function(e, t) {
					this.createOptionValue(t)
				}, this))
			} else {
				cached_function.apply(this, arguments);
			}
		};
	}());
	
	

$(document).ready(function(){
  $('#example-multiple-optgroups').multiselect({
    enableCollapsibleOptGroups: true
  });  
});
		</script>
</html>	

Explanation:

In the above example, we created an example of jQuery bootstrap select plugin with multiple option selection. In this we can select multiple value from dropdown list.

Output:

Following is the output of this example.

Next TopicFroala editor plugin