Widget factory

You can create new widgets from scratch, using just the $.Widget object as a base to inherit from, or you can explicitly inherit from existing jQuery UI or third-party widgets. Defining a widget with the same name as you inherit from even allows you to extend widgets in place.

jQuery UI contains many widgets that maintain state and therefore have a slightly different usage pattern than typical jQuery plugins. All of jQuery UI's widgets use the same patterns, which is defined by the widget factory. So if you learn how to use one widget, then you'll know how to use all of them.

Looking for tutorials about the widget factory? Check out the articles on the jQuery Learning Center.

Note: This documentation shows examples using the progressbar widget but the syntax is the same for every widget.

Initialization

In order to track the state of the widget, we must introduce a full life cycle for the widget. The life cycle starts when the widget is initialized. To initialize a widget, we simply call the plugin on one or more elements.

$( "#elem" ).progressbar();

This will initialize each element in the jQuery object, in this case the element with an id of "elem".

Options

Because progressbar() was called with no parameters, the widget was initialized with its default options. We can pass a set of options during initialization to override the defaults:

$( "#elem" ).progressbar({ value: 20 });

We can pass as many or as few options as we want during initialization. Any options that we don't pass will just use their default values.

You can pass multiple options arguments. Those arguments will be merged into one object (similar to $.extend( true, target, object1, objectN )). This is useful for sharing options between instances, while overriding some properties for each one:

var options = { modal: true, show: "slow" };
$( "#dialog1" ).dialog( options );
$( "#dialog2" ).dialog( options, { autoOpen: false });

All options passed on init are deep-copied to ensure the objects can be modified later without affecting the widget. Arrays are the only exception, they are referenced as-is. This exception is in place to support data-binding, where the data source has to be kept as a reference.

The default values are stored on the widget's prototype, therefore we have the ability to override the values that jQuery UI sets. For example, after setting the following, all future progressbar instances will default to a value of 80:

$.ui.progressbar.prototype.options.value = 80;

The options are part of the widget's state, so we can set options after initialization as well. We'll see this later with the option method.

Methods

Now that the widget is initialized, we can query its state or perform actions on the widget. All actions after initialization take the form of a method call. To call a method on a widget, we pass the name of the method to the jQuery plugin. For example, to call the value() method on our progressbar widget, we would use:

$( "#elem" ).progressbar( "value" );

If the method accepts parameters, we can pass them after the method name. For example, to pass the parameter 40 to the value() method, we can use:

$( "#elem" ).progressbar( "value", 40 );

Just like other methods in jQuery, most widget methods return the jQuery object for chaining.

$( "#elem" )
  .progressbar( "value", 90 )
  .addClass( "almost-done" );

Each widget will have its own set of methods based on the functionality that the widget provides. However, there are a few methods that exist on all widgets, which are documented below.

Events

All widgets have events associated with their various behaviors to notify you when the state is changing. For most widgets, when the events are triggered, the names are prefixed with the widget name and lowercased. For example, we can bind to progressbar's change event which is triggered whenever the value changes.

$( "#elem" ).bind( "progressbarchange", function() {
  alert( "The value has changed!" );
});

Each event has a corresponding callback, which is exposed as an option. We can hook into progressbar's change callback instead of binding to the progressbarchange event, if we want to.

$( "#elem" ).progressbar({
  change: function() {
    alert( "The value has changed!" );
  }
});

All widgets have a create event which is triggered upon instantiation.

Instance

The widget's instance can be retrieved from a given element using the instance() method.

$( "#elem" ).progressbar( "instance" );

If the instance() method is called on an element that is not associated with the widget, undefined is returned.

$( "#not-a-progressbar" ).progressbar( "instance" ); // undefined

The instance is stored using jQuery.data() with the widget's full name as the key. Therefore, the :data selector can also determine whether an element has a given widget bound to it.

$( "#elem" ).is( ":data('ui-progressbar')" ); // true
$( "#elem" ).is( ":data('ui-draggable')" ); // false

Unlike instance(), :data can be used even if the widget being tested for has not loaded.

$( "#elem" ).nonExistentWidget( "instance" ); // TypeError
$( "#elem" ).is( ":data('ui-nonExistentWidget')" ); // false

You can also use :data to get a list of all elements that are instances of a given widget.

$( ":data('ui-progressbar')" );

Properties

All widgets have the following set of properties:

• defaultElement: An element to use when a widget instance is constructed without providing an element. For example, since the progressbar's defaultElement is "<div>", $.ui.progressbar({ value: 50 }) instantiates a progressbar widget instance on a newly created <div>.
• document: A jQuery object containing the document that the widget's element is within. Useful if you need to interact with widgets within iframes.
• element: A jQuery object containing the element used to instantiate the widget. If you select multiple elements and call .myWidget(), a separate widget instance will be created for each element. Therefore, this property will always contain one element.
• namespace: The location on the global jQuery object that the widget's prototype is stored on. For example a namespace of "ui" indicates that the widget's prototype is stored on $.ui.
• options: An object containing the options currently being used by the widget. On instantiation, any options provided by the user will automatically be merged with any default values defined in $.myNamespace.myWidget.prototype.options. User specified options override the defaults.
• uuid: A unique integer identifier for the widget.
• version: The string version of the widget. For jQuery UI widgets this will be set to the version of jQuery UI the widget is using. Widget developers have to set this property in their prototype explicitly.
• widgetEventPrefix: The prefix prepended to the name of events fired from this widget. For example the widgetEventPrefix of the draggable widget is "drag", therefore when a draggable is created, the name of the event fired is "dragcreate". By default the widgetEventPrefix of a widget is its name. Note: This property is deprecated and will be removed in a later release. Event names will be changed to widgetName:eventName (e.g. "draggable:create").
• widgetFullName: The full name of the widget including the namespace. For $.widget( "myNamespace.myWidget", {} ), widgetFullName will be "myNamespace-myWidget".
• widgetName: The name of the widget. For $.widget( "myNamespace.myWidget", {} ), widgetName will be "myWidget".
• window: A jQuery object containing the window that the widget's element is within. Useful if you need to interact with widgets within iframes.

The name of the widget to create, including the namespace.

The base widget to inherit from. This must be a constructor that can be instantiated with the `new` keyword. Defaults to jQuery.Widget.

The object to use as a prototype for the widget.

Code examples:

Initialize the widget with the disabled option specified:

$( ".selector" ).widget({
  disabled: true
});

Get or set the disabled option, after initialization:

// Getter
var disabled = $( ".selector" ).widget( "option", "disabled" );
 
// Setter
$( ".selector" ).widget( "option", "disabled", true );

Multiple types supported:

• Boolean: When set to false, no animation will be used and the element will be hidden immediately. When set to true, the element will fade out with the default duration and the default easing.
• Number: The element will fade out with the specified duration and the default easing.
• String: The element will be hidden using the specified effect. The value can either be the name of a built-in jQuery animation method, such as "slideUp", or the name of a jQuery UI effect, such as "fold". In either case the effect will be used with the default duration and the default easing.
• Object: If the value is an object, then effect, delay, duration, and easing properties may be provided. If the effect property contains the name of a jQuery method, then that method will be used; otherwise it is assumed to be the name of a jQuery UI effect. When using a jQuery UI effect that supports additional settings, you may include those settings in the object and they will be passed to the effect. If duration or easing is omitted, then the default values will be used. If effect is omitted, then "fadeOut" will be used. If delay is omitted, then no delay is used.

Code examples:

Initialize the widget with the hide option specified:

$( ".selector" ).widget({
  hide: { effect: "explode", duration: 1000 }
});

Get or set the hide option, after initialization:

// Getter
var hide = $( ".selector" ).widget( "option", "hide" );
 
// Setter
$( ".selector" ).widget( "option", "hide", { effect: "explode", duration: 1000 } );

Multiple types supported:

• Boolean: When set to false, no animation will be used and the element will be shown immediately. When set to true, the element will fade in with the default duration and the default easing.
• Number: The element will fade in with the specified duration and the default easing.
• String: The element will be shown using the specified effect. The value can either be the name of a built-in jQuery animation method, such as "slideDown", or the name of a jQuery UI effect, such as "fold". In either case the effect will be used with the default duration and the default easing.
• Object: If the value is an object, then effect, delay, duration, and easing properties may be provided. If the effect property contains the name of a jQuery method, then that method will be used; otherwise it is assumed to be the name of a jQuery UI effect. When using a jQuery UI effect that supports additional settings, you may include those settings in the object and they will be passed to the effect. If duration or easing is omitted, then the default values will be used. If effect is omitted, then "fadeIn" will be used. If delay is omitted, then no delay is used.

Code examples:

Initialize the widget with the show option specified:

$( ".selector" ).widget({
  show: { effect: "blind", duration: 800 }
});

Get or set the show option, after initialization:

// Getter
var show = $( ".selector" ).widget( "option", "show" );
 
// Setter
$( ".selector" ).widget( "option", "show", { effect: "blind", duration: 800 } );

• This method does not accept any arguments.

_create: function() {
  this.element.css( "background-color", this.options.color );
}

• fn
  Type: Function() or String
  The function to invoke. Can also be the name of a method on the widget.
• delay
  Type: Number
  The number of milliseconds to wait before invoking the function. Defaults to 0.

this._delay( this._foo, 100 );

• This method does not accept any arguments.

_destroy: function() {
  this.element.removeClass( "my-widget" );
}

• element
  Type: jQuery
  The element(s) to apply the focusable behavior to.

this._focusable( this.element.find( ".my-items" ) );

• This method does not accept any arguments.

_getCreateEventData: function() {
  return this.options;
}

• This method does not accept any arguments.

_getCreateOptions: function() {
  return { id: this.element.attr( "id" ) };
}

• element
  Type: jQuery
  The element(s) to hide.
• option
  Type: Object
  The properties defining how to hide the element.
• callback
  Type: Function()
  Callback to invoke after the element has been fully hidden.

this._hide( this.element, this.options.hide, function() {
 
  // Remove the element from the DOM when it's fully hidden.
  $( this ).remove();
});

• element
  Type: jQuery
  The element(s) to apply the hoverable behavior to.

this._hoverable( this.element.find( "div" ) );

• This method does not accept any arguments.

_init: function() {
  if ( this.options.autoOpen ) {
    this.open();
  }
}

• element
  Type: jQuery
  The element(s) to unbind the event handlers from. Unlike the _on() method, the elements are required for _off().
• eventName
  Type: String
  One or more space-separated event types.

this._off( this.element, "click" );

• suppressDisabledCheck (default: false)
  Type: Boolean
  Whether or not to bypass the disabled check.
• element
  Type: jQuery
  Which element(s) to bind the event handlers to. If no element is provided, this.element is used for non-delegated events and the widget element is used for delegated events.
• handlers
  Type: Object
  An object in which the keys represent the event type and optional selector for delegation, and the values represent a handler function to be called for the event.

this._on( this.element, {
  "click a": function( event ) {
    event.preventDefault();
  }
});

• key
  Type: String
  The name of the option to set.
• value
  Type: Object
  A value to set for the option.

_setOption: function( key, value ) {
  if ( key === "width" ) {
    this.element.width( value );
  }
  if ( key === "height" ) {
    this.element.height( value );
  }
  this._super( key, value );
}

• options
  Type: Object
  An object containing options to set, with the name of the option as the key and the option value as the value.

_setOptions: function( options ) {
  var that = this,
    resize = false;
 
  $.each( options, function( key, value ) {
    that._setOption( key, value );
    if ( key === "height" || key === "width" ) {
      resize = true;
    }
  });
 
  if ( resize ) {
    this.resize();
  }
}

• element
  Type: jQuery
  The element(s) to show.
• option
  Type: Object
  The properties defining how to show the element.
• callback
  Type: Function()
  Callback to invoke after the element has been fully shown.

this._show( this.element, this.options.show, function() {
 
  // Focus the element when it's fully visible.
  this.focus();
}

• arg
  Type: Object
  Zero to many arguments to pass to the parent widget's method.

_setOption: function( key, value ) {
  if ( key === "title" ) {
    this.element.find( "h3" ).text( value );
  }
  this._super( key, value );
}

• arguments
  Type: Array
  Array of arguments to pass to the parent method.

_setOption: function( key, value ) {
  if ( key === "title" ) {
    this.element.find( "h3" ).text( value );
  }
  this._superApply( arguments );
}

• type
  Type: String
  The type should match the name of a callback option. The full event type will be generated automatically.
• event
  Type: Event
  The original event that caused this event to occur; useful for providing context to the listener.
• data
  Type: Object
  A hash of data associated with the event.

this._on( this.element, {
  keydown: function( event ) {
 
    // Pass the original event so that the custom search event has
    // useful information, such as keyCode
    this._trigger( "search", event, {
 
      // Pass additional information unique to this event
      value: this.element.val()
    });
  }
});

• This method does not accept any arguments.

• This method does not accept any arguments.

• This method does not accept any arguments.

• This method does not accept any arguments.

• optionName
  Type: String
  The name of the option to get.

• This signature does not accept any arguments.

• optionName
  Type: String
  The name of the option to set.
• value
  Type: Object
  A value to set for the option.

• options
  Type: Object
  A map of option-value pairs to set.

• This method does not accept any arguments.

• event
  Type: Event
• ui
  Type: Object

Note: The ui object is empty but included for consistency with other events.

$( ".selector" ).widget({
  create: function( event, ui ) {}
});

$( ".selector" ).on( "widgetcreate", function( event, ui ) {} );