Bootstrap - Collapse Plugin

The collapse plugin makes it easy to make collapsing divisions of the page. Whether you use it to build an accordion navigation or content boxes, it allows for a lot of content options.

If you want to include this plugin functionality individually, then you will need the collapse.js. This also requires the Transition Plugin to be included in your version of Bootstrap. Else, as mentioned in the chapter Bootstrap Plugins Overview, you can include the bootstrap.js or the minified bootstrap.min.js.

You can use the collapse plugin −

• To create collapsible groups or accordion. This can be created as in the sample example below −

<div class = "panel-group" id = "accordion">
   <div class = "panel panel-default">
      
      <div class = "panel-heading">
         <h4 class = "panel-title">
            <a data-toggle = "collapse" data-parent = "#accordion" href = "#collapseOne">
               Click me to expand. Click me again to collapse.Section 1
            </a>
         </h4>
      </div>
      
      <div id = "collapseOne" class = "panel-collapse collapse in">
         <div class = "panel-body">
            Nihil anim keffiyeh helvetica, craft beer labore wes anderson cred 
               nesciunt sapiente ea proident. Ad vegan excepteur butcher vice lomo.
         </div>
      </div>
      
   </div>
   
   <div class = "panel panel-default">
      <div class = "panel-heading">
         <h4 class = "panel-title">
            <a data-toggle = "collapse" data-parent = "#accordion" href = "#collapseTwo">
               Click me to expand. Click me again to collapse.Section 2
            </a>
         </h4>
      </div>

      <div id = "collapseTwo" class = "panel-collapse collapse">
         <div class = "panel-body">
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               sapiente ea proident. Ad vegan excepteur butcher vice lomo.
         </div>
      </div>
      
   </div>
   
   <div class = "panel panel-default">
      <div class = "panel-heading">
         <h4 class = "panel-title">
            <a data-toggle = "collapse" data-parent = "#accordion" href = "#collapseThree">
               Click me to expand. Click me again to collapse.Section 3
            </a>
         </h4>
      </div>
     
      <div id = "collapseThree" class = "panel-collapse collapse">
         <div class = "panel-body">
            Nihil anim keffiyeh helvetica, craft beer labore wes anderson cred nesciunt 
               sapiente ea proident. Ad vegan excepteur butcher vice lomo.
         </div>
      </div>
     
   </div>
</div>

• data-toggle = "collapse" is added to the link on which you click to expand or collapse the component.
• href or a data-target attribute is added to the parent component, whose value is id of the child component.
• data-parent attribute is added for creating the accordion like effect.

• To create simple collapsible without the accordion markup − This can be created as in the sample example below −

<button type = "button" class = "btn btn-primary" data-toggle = "collapse" data-target = "#demo">
   simple collapsible
</button>

<div id = "demo" class = "collapse in">
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      sapiente ea proident. Ad vegan excepteur butcher vice lomo.
</div>

As you can see in the example we have created a simple collapsible component, unlike accordion, we haven't added the attribute data-parent.

Usage

Following table lists the classes that the collapse plugin utilizes to handle the heavy lifting −

Class	Description
.collapse	Hides the content.
.collapse.in	Shows the content.
.collapsing	Is added when the transition starts, and removed when it finishes.

You can use collapse plugin in two ways −

• Via data attributes − Add data-toggle = "collapse" and a data-target to the element to automatically assign control of a collapsible element. The data-target attribute will accept a CSS selector to apply the collapse to. Be sure to add the class .collapse to the collapsible element. If you’d like it to default open, include the additional class .in.
  To add accordion-like group management to a collapsible control, add the data attribute data-parent = "#selector".
• Via JavaScript − The collapse method can be activated with JavaScript as shown below −
  

$('.collapse').collapse()

Options

There are certain options which can be passed via data attributes or JavaScript are listed in the following table −

Option Name	Type/Default Value	Data attribute name	Description
parent	selector Default − false	data-parent	If selector is false, then all collapsible elements under the specified parent will be closed (similar to traditional accordion behavior - this dependent on the accordion-group class).
toggle	boolean Default − true	data-toggle	Toggles the collapsible element on invocation.

Methods

Here is a list of some useful methods that are used with collapsible elements.

Method	Description	Example
Options − .collapse(options)	Activates your content as a collapsible element. Accepts an optional options object.	$('#identifier').collapse({ toggle: false })
Toggle − .collapse('toggle')	Toggles a collapsible element to shown or hidden.	$('#identifier').collapse('toggle')
Show − .collapse('show')	Shows a collapsible element.	$('#identifier').collapse('show')
Hide − .collapse('hide')	Hides a collapsible element.	$('#identifier').collapse('hide')

Example

The following example demonstrates the usage of methods −

<div class = "panel-group" id = "accordion">
   <div class = "panel panel-default">
      
      <div class = "panel-heading">
         <h4 class = "panel-title">
            <a data-toggle = "collapse" data-parent = "#accordion" href = "#collapseOne">
               Click me to expand. Click me again to collapse. Section 1--hide method
            </a>
         </h4>
      </div>
      
      <div id = "collapseOne" class = "panel-collapse collapse in">
         <div class = "panel-body">
            Nihil anim keffiyeh helvetica, craft beer labore wes anderson cred nesciunt 
               sapiente ea proident. Ad vegan excepteur butcher vice lomo.
         </div>
      </div>
      
   </div>
   
   <div class = "panel panel-success">
      <div class = "panel-heading">
         <h4 class = "panel-title">
            <a data-toggle = "collapse" data-parent = "#accordion" href = "#collapseTwo">
               Click me to expand. Click me again to collapse. Section 2--show method
            </a>
         </h4>
      </div>
      
      <div id = "collapseTwo" class = "panel-collapse collapse">
         <div class = "panel-body">
            Nihil anim keffiyeh helvetica, craft beer labore wes anderson cred nesciunt 
               sapiente ea proident. Ad vegan excepteur butcher vice lomo.
         </div>
      </div>
      
   </div>
   
   <div class = "panel panel-info">
      <div class = "panel-heading">
         <h4 class = "panel-title">
            <a data-toggle = "collapse" data-parent = "#accordion" href = "#collapseThree">
               Click me to expand. Click me again to collapse. Section 3--toggle method
            </a>
         </h4>
      </div>
      
      <div id = "collapseThree" class = "panel-collapse collapse">
         <div class = "panel-body">
            Nihil anim keffiyeh helvetica, craft beer labore wes anderson cred nesciunt 
               sapiente ea proident. Ad vegan excepteur butcher vice lomo.
         </div>
      </div>
   </div>
   
   <div class = "panel panel-warning">
      <div class = "panel-heading">
         <h4 class = "panel-title">
            <a data-toggle = "collapse" data-parent = "#accordion" href = "#collapseFour">
               Click me to expand. Click me again to collapse. Section 4--options method
            </a>
         </h4>
      </div>
      
      <div id = "collapseFour" class = "panel-collapse collapse">
         <div class = "panel-body">
            Nihil anim keffiyeh helvetica, craft beer labore wes anderson cred nesciunt 
               sapiente ea proident. Ad vegan excepteur butcher vice lomo.
         </div>
      </div>
      
   </div>
</div>

<script type = "text/javascript">
   $(function () { $('#collapseFour').collapse({
      toggle: false
   })});
  
   $(function () { $('#collapseTwo').collapse('show')});
   $(function () { $('#collapseThree').collapse('toggle')});
   $(function () { $('#collapseOne').collapse('hide')});
</script>  

Events

The following table lists a few events that can be used with the collapse functionality.

Event	Description	Example
show.bs.collapse	Fired after the show method is called.	$('#identifier').on('show.bs.collapse', function () { // do something })
shown.bs.collapse	This event is fired when a collapse element has been made visible to the user (will wait for CSS transitions to complete).	$('#identifier').on('shown.bs.collapse', function () { // do something })
hide.bs.collapse	Fired when the hide instance method has been called.	$('#identifier').on('hide.bs.collapse', function () { // do something })
hidden.bs.collapse	This event is fired when a collapse element has been hidden from the user (will wait for CSS transitions to complete).	$('#identifier').on('hidden.bs.collapse', function () { // do something })

Example

The following example demonstrates the usage of events −

<div class = "panel-group" id = "accordion">
   <div class = "panel panel-info">
   
      <div class = "panel-heading">
         <h4 class = "panel-title">
            <a data-toggle = "collapse" data-parent = "#accordion" href = "#collapseexample">
               Click me to expand. Click me again to collapse. Section --shown event
            </a>
         </h4>
      </div>
      
      <div id = "collapseexample" class = "panel-collapse collapse">
         <div class = "panel-body">
            Nihil anim keffiyeh helvetica, craft beer labore wes anderson cred nesciunt
               sapiente ea proident. Ad vegan excepteur butcher vice lomo.
         </div>
      </div>
      
   </div>
</div>

<script type = "text/javascript">
   $(function () { 
      $('#collapseexample').on('show.bs.collapse', function () {
         alert('Hey, this alert shows up when you expand it');
      })
   });
</script>