Collapse

The Bootstrap-Vue <b-collapse> component and v-b-toggle directive allows you to toggle content visibility on your pages. Includes support for making accordions.

<div>
  <b-btn v-b-toggle.collapse1 variant="primary">Toggle Collapse</b-btn>
  <b-collapse id="collapse1" class="mt-2">
    <b-card>
      <p class="card-text">Collapse contents Here</p>
      <b-btn v-b-toggle.collapse1_inner size="sm">Toggle Inner Collapse</b-btn>
      <b-collapse id=collapse1_inner class="mt-2">
        <b-card>Hello!</b-card>
      </b-collapse>
    </b-card>
  </b-collapse>
</div>

<!-- collapse-1.vue -->

Usage

Other elements can easily toggle <b-collapse> components using the v-b-toggle directive.

<div>
  <!-- Using modifiers -->
  <b-btn v-b-toggle.collapse2 class="m-1">Toggle Collapse</b-btn>

  <!-- Using value -->
  <b-btn v-b-toggle="'collapse2'" class="m-1">Toggle Collapse</b-btn>

  <!-- element to collapse -->
  <b-collapse id="collapse2">
    <b-card>
      I am collapsable content!
    </b-card>
  </b-collapse>
</div>

<!-- collapse-2.vue -->

Initial visibility (start expanded)

To make the <b-collapse> show initially, set the visible prop:

<div>
  <b-btn v-b-toggle.collapse3 class="m-1">Toggle Collapse</b-btn>
  <b-collapse visible id="collapse3">
    <b-card>
      I should start open!
    </b-card>
  </b-collapse>
</div>

<!-- collapse-3.vue -->

v-model support

The component's collapsed (visible) state can also be set with v-model which binds internally to the visible prop.

Note, when using v-model to control <b-collapse>, the aria-* attributes and class collapsed are not automaticaly placed on the trigger button (as is the case when using the v-b-toggle directive). In this example we must control them ourselves.

<template>
  <div>
    <b-btn @click="showCollapse = !showCollapse"
           :class="showCollapse ? 'collapsed' : null"
           aria-controls="collapse4"
           :aria-expanded="showCollapse ? 'true' : 'false'">
      Toggle Collapse
    </b-btn>
    <b-collapse class="mt-2" v-model="showCollapse" id="collapse4">
      <b-card>
        I should start open!
      </b-card>
    </b-collapse>
  </div>
</template>

<script>
export default {
  data () {
    return {
      showCollapse: true
    }
  }
}
</script>

<-- collapse-4.vue -->

Trigger multiple collapse elements

You can even collapse multiple <b-collapse> components via a single v-b-toggle by providing multiple target IDs using modifers:

<div>
  <!-- Single button triggers two b-collapse components -->
  <b-btn v-b-toggle.collapseA.collapseB>Toggle Both Collapse A and B</b-btn>

  <!-- elements to collapse -->
  <b-collapse id="collapseA" class="mt-2">
    <b-card>
      I am collapsable content A!
    </b-card>
  </b-collapse>
  <b-collapse id="collapseB" class="mt-2">
    <b-card>
      I am collapsable content B!
    </b-card>
  </b-collapse>
</div>

<!-- collapse-mult-1.vue -->

Accordion Support

Turn a group of <b-collapse> components into an accordion by supplying an accordion group identifier via the accordion prop:

<template>
  <div role="tablist">
    <b-card no-body class="mb-1">
      <b-card-header header-tag="header" class="p-1" role="tab">
        <b-btn block href="#" v-b-toggle.accordion1 variant="info">Accordion 1</b-btn>
      </b-card-header>
      <b-collapse id="accordion1" visible accordion="my-accordion" role="tabpanel">
        <b-card-body>
          <p class="card-text">
            I start opened because <code>visible</code> is <code>true</code>
          </p>
          <p class="card-text">
            {{ text }}
          </p>
        </b-card-body>
      </b-collapse>
    </b-card>
    <b-card no-body class="mb-1">
      <b-card-header header-tag="header" class="p-1" role="tab">
        <b-btn block href="#" v-b-toggle.accordion2 variant="info">Accordion 2</b-btn>
      </b-card-header>
      <b-collapse id="accordion2" accordion="my-accordion" role="tabpanel">
        <b-card-body>
          <p class="card-text">
            {{ text }}
          </p>
        </b-card-body>
      </b-collapse>
    </b-card>
    <b-card no-body class="mb-1">
      <b-card-header header-tag="header" class="p-1" role="tab">
        <b-btn block href="#" v-b-toggle.accordion3 variant="info">Accordion 3</b-btn>
      </b-card-header>
      <b-collapse id="accordion3" accordion="my-accordion" role="tabpanel">
        <b-card-body>
          <p class="card-text">
            {{ text }}
          </p>
        </b-card-body>
      </b-collapse>
    </b-card>
  </div>
</template>

<script>
export default {
  data () {
    return {
      text: `
        Anim pariatur cliche reprehenderit, enim eiusmod high life accusamus terry
        richardson ad squid. 3 wolf moon officia aute, non cupidatat skateboard dolor
        brunch. Food truck quinoa nesciunt laborum eiusmod. Brunch 3 wolf moon
        tempor, sunt aliqua put a bird on it squid single-origin coffee nulla
        assumenda shoreditch et. Nihil anim keffiyeh helvetica, craft beer labore
        wes anderson cred nesciunt sapiente ea proident. Ad vegan excepteur butcher
        vice lomo. Leggings occaecat craft beer farm-to-table, raw denim aesthetic
        synth nesciunt you probably haven't heard of them accusamus labore VHS.
      `
    }
  }
}
</script>

<!-- accordion-1.vue -->

Notes:

• When using accordion mode, make sure you place the trigger elements and <b-collapse> components inside an element with role="tablist" and set role="tab" on each trigger element's container (each trigger element should be wrapped) in order to help screen reader users navigate the accordion group.
• If using the v-model feature of <b-collaspe> in accordion mode, do not bind the v-model or visible prop of all the collapses in the accordion group to the same variable!
• Ensure, at most, only one <b-collapse> in the accordion group has the visible prop and/or v-model set to true.

Hiding and showing content in the toggle button based on collapse state

When using the v-b-toggle directive, the class collapsed will automatically be placed on the trigger element when the collapse is closed, and removed when open. You can use this class to display or hide content within the togger via custom CSS:

Example HTML markup:

<b-btn v-b-toggle.myCollapse>
  <span class="when-opened">Close</span>
  <span class="when-closed">Open</span>
  My Collapse
</b-btn>
<b-collapse id="myCollapse">
  <!-- content here -->
</b-collapse>

Example Custom CSS:

.collapsed > .when-opened,
:not(.collapsed) > .when-closed {
  display: none;
}

Accessibility

The v-b-toggle directive will automatically add the ARIA attributes aria-controls and aria-expanded to the component that the directive appears on (as well as add the class collapsed when not expanded). aria-expanded will reflect the state of the tartget <b-collapse> component, while aria-controls will be set to the ID(s) of the target <b-collapse> component(s).

If using v-model to set the visible state instead of the directive v-b-toggle, you will be required to, on the toggle element, add the aria-controls and other appropriate attributes and classes yourself.

While the v-b-toggle directive can be placed on almost any HTML element or Vue component, it is reccomended to use a button or link (or similar component) to act as your toggler. Otherwise your trigger elements may be inaccessible to keyboard or screen reader users. If you do place them on something other than a button or link (or similar component), you should add the attributes tabindex="0" and role="button" to allow users of assistive technology to reach your trigger element.

When using accordion mode, make sure you place the trigger elements and <b-collapse> components inside an element with role="tablist" and set role="tab" on each trigger element's container in order to help screen reader users navigate the accordion group. Unfortunately, Boostrap-Vue cannont apply those roles for you automaticaly, as it depends on your final document markup.

Component Reference