<div>
<b-button v-b-toggle.collapse-1 variant="primary">Toggle Collapse</b-button>
<b-collapse id="collapse-1" class="mt-2">
<b-card>
<p class="card-text">Collapse contents Here</p>
<b-button v-b-toggle.collapse-1-inner size="sm">Toggle Inner Collapse</b-button>
<b-collapse id="collapse-1-inner" class="mt-2">
<b-card>Hello!</b-card>
</b-collapse>
</b-card>
</b-collapse>
</div>
Usage
Other elements can easily toggle <b-collapse> components using the v-b-toggle directive.
<div>
<b-button v-b-toggle.collapse-2 class="m-1">Toggle Collapse</b-button>
<b-button v-b-toggle="'collapse-2'" class="m-1">Toggle Collapse</b-button>
<b-collapse id="collapse-2">
<b-card>I am collapsible content!</b-card>
</b-collapse>
</div>
See the v-b-toggle directive documentation for detailed usage information.
Initial visibility (start expanded)
To make the <b-collapse> show initially, set the visible prop:
<div>
<b-button v-b-toggle.collapse-3 class="m-1">Toggle Collapse</b-button>
<b-collapse visible id="collapse-3">
<b-card>I should start open!</b-card>
</b-collapse>
</div>
By default, an initially visible collapse will not animate on mount. To enable the collapse expanding animation on mount (when visible or v-model is true), set the appear prop on <b-collapse>.
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 automatically placed on the trigger button (as is the case when using the v-b-toggle directive). In this example we must control the attributes ourselves for proper accessibility support.
<template>
<div>
<b-button
:class="visible ? null : 'collapsed'"
:aria-expanded="visible ? 'true' : 'false'"
aria-controls="collapse-4"
@click="visible = !visible"
>
Toggle Collapse
</b-button>
<b-collapse id="collapse-4" v-model="visible" class="mt-2">
<b-card>I should start open!</b-card>
</b-collapse>
</div>
</template>
<script>
export default {
data() {
return {
visible: true
}
}
}
</script>
Trigger multiple collapse elements
You can even collapse multiple <b-collapse> components via a single v-b-toggle by providing multiple target IDs using modifiers.
You can also pass multiple target IDs via the directive value in BootstrapVue release v2.14.0+.
<div>
<b-button v-b-toggle.collapse-a.collapse-b>Toggle Collapse A and B</b-button>
<b-button v-b-toggle="'collapse-a collapse-b'">Toggle Collapse A and B</b-button>
<b-button v-b-toggle="['collapse-a', 'collapse-b']">Toggle Collapse A and B</b-button>
<b-collapse id="collapse-a" class="mt-2">
<b-card>I am collapsible content A!</b-card>
</b-collapse>
<b-collapse id="collapse-b" class="mt-2">
<b-card>I am collapsible content B!</b-card>
</b-collapse>
</div>
Accordion support
Turn a group of <b-collapse> components into an accordion by supplying an accordion group identifier via the accordion prop. Note that only one collapse in an accordion group can be open at a time.
<template>
<div class="accordion" role="tablist">
<b-card no-body class="mb-1">
<b-card-header header-tag="header" class="p-1" role="tab">
<b-button block v-b-toggle.accordion-1 variant="info">Accordion 1</b-button>
</b-card-header>
<b-collapse id="accordion-1" visible accordion="my-accordion" role="tabpanel">
<b-card-body>
<b-card-text>I start opened because <code>visible</code> is <code>true</code></b-card-text>
<b-card-text>{{ text }}</b-card-text>
</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-button block v-b-toggle.accordion-2 variant="info">Accordion 2</b-button>
</b-card-header>
<b-collapse id="accordion-2" accordion="my-accordion" role="tabpanel">
<b-card-body>
<b-card-text>{{ text }}</b-card-text>
</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-button block v-b-toggle.accordion-3 variant="info">Accordion 3</b-button>
</b-card-header>
<b-collapse id="accordion-3" accordion="my-accordion" role="tabpanel">
<b-card-body>
<b-card-text>{{ text }}</b-card-text>
</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>
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-collapse> 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. Only one collapse in an accordion group can be open at a time.
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 toggle via custom CSS. As of BootstrapVue 2.14.0, the class not-collapsed will be applied when the target(s) are not closed.
Example HTML markup:
<div>
<b-button v-b-toggle:my-collapse>
<span class="when-open">Close</span><span class="when-closed">Open</span> My Collapse
</b-button>
<b-collapse id="my-collapse">
</b-collapse>
</div>Example Custom CSS:
.collapsed > .when-open,
.not-collapsed > .when-closed {
display: none;
}'Global' $root instance events
Using $root instance it is possible to emit and listen events somewhere out of a component, where <b-collapse> is used. In short, $root behaves like a global event emitters and listener. Details about $root instance can be found in the official Vue docs.
Listening to collapses state changes via $root events
To listen to any collapse state changes, use:
export default {
mounted() {
this.$root.$on('bv::collapse::state', (collapseId, isJustShown) => {
console.log('collapseId:', collapseId)
console.log('isJustShown:', isJustShown)
})
}
}where collapseId is collapse id which changed its state; isJustShown is true/false, i.e. shown/hidden collapse.
Toggling collapses via $root events
To toggle (open/close) a specific collapse, pass the collapse id:
this.$root.$emit('bv::toggle::collapse', 'my-collapse-id')Optionally scoped default slot
New in v2.2.0
The default slot can be optionally scoped. The following scope properties are available:
| Property | Type | Description |
visible | Boolean | Visible state of the collapse |
close | Function | When called, will close the collapse |
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 target <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 recommended 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, BootstrapVue cannot apply those roles for you automatically, as it depends on your final document markup.
Note: The animation effect of this component is dependent on the prefers-reduced-motion media query. See the reduced motion section of our accessibility documentation for additional details.
See also