--- layout: docs title: Collapse group: components --- The Bootstrap collapse plugin allows you to toggle content on your pages with a bit of JavaScript and some classes. Flexible plugin that utilizes a handful of classes (from the **required [transitions plugin]({{ site.baseurl }}/components/transitions/)**) for easy toggle behavior. ## Contents * Will be replaced with the ToC, excluding the "Contents" header {:toc} ## Example Click the buttons below to show and hide another element via class changes: - `.collapse` hides content - `.collapsing` is applied during transitions - `.collapse.in` shows content You can use a link with the `href` attribute, or a button with the `data-target` attribute. In both cases, the `data-toggle="collapse"` is required. {% example html %}

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{% endexample %} ## Accordion example Extend the default collapse behavior to create an accordion. {% example html %}
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{% endexample %} ## Accessibility Be sure to add `aria-expanded` to the control element. This attribute explicitly defines the current state of the collapsible element to screen readers and similar assistive technologies. If the collapsible element is closed by default, it should have a value of `aria-expanded="false"`. If you've set the collapsible element to be open by default using the `in` class, set `aria-expanded="true"` on the control instead. The plugin will automatically toggle this attribute based on whether or not the collapsible element has been opened or closed. Additionally, if your control element is targeting a single collapsible element – i.e. the `data-target` attribute is pointing to an `id` selector – you may add an additional `aria-controls` attribute to the control element, containing the `id` of the collapsible element. Modern screen readers and similar assistive technologies make use of this attribute to provide users with additional shortcuts to navigate directly to the collapsible element itself. ## Usage The collapse plugin utilizes a few classes to handle the heavy lifting: - `.collapse` hides the content - `.collapse.in` shows the content - `.collapsing` is added when the transition starts, and removed when it finishes These classes can be found in `_animation.scss`. ### Via data attributes Just add `data-toggle="collapse"` and a `data-target` to the element to automatically assign control of a collapsible element. The `data-target` attribute accepts 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, add the additional class `in`. To add accordion-like group management to a collapsible control, add the data attribute `data-parent="#selector"`. Refer to the demo to see this in action. ### Via JavaScript Enable manually with: {% highlight js %} $('.collapse').collapse() {% endhighlight %} ### Options Options can be passed via data attributes or JavaScript. For data attributes, append the option name to `data-`, as in `data-parent=""`.
Name Type Default Description
parent selector false If a selector is provided, then all collapsible elements under the specified parent will be closed when this collapsible item is shown. (similar to traditional accordion behavior - this is dependent on the panel class)
toggle boolean true Toggles the collapsible element on invocation
### Methods #### `.collapse(options)` Activates your content as a collapsible element. Accepts an optional options `object`. {% highlight js %} $('#myCollapsible').collapse({ toggle: false }) {% endhighlight %} #### `.collapse('toggle')` Toggles a collapsible element to shown or hidden. #### `.collapse('show')` Shows a collapsible element. #### `.collapse('hide')` Hides a collapsible element. ### Events Bootstrap's collapse class exposes a few events for hooking into collapse functionality.
Event Type Description
show.bs.collapse This event fires immediately when the show instance method is called.
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).
hide.bs.collapse This event is fired immediately when the hide method has been called.
hidden.bs.collapse This event is fired when a collapse element has been hidden from the user (will wait for CSS transitions to complete).
{% highlight js %} $('#myCollapsible').on('hidden.bs.collapse', function () { // do something… }) {% endhighlight %}