README.md

Vue Collapsed

Dynamic CSS height transition from any to auto and vice versa. Accordion ready.

Examples and Demo - Stackblitz

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Installation

npm i vue-collapsed
# yarn add vue-collapsed
# pnpm add vue-collapsed
# bun add vue-collapsed

Props

Name	Description	Type	Required
when	Value to control collapse	boolean	✅
baseHeight	Collapsed height in px, defaults to 0.	number	❌
as	Tag to use instead of div	keyof HTMLElementTagNameMap	❌

Emits

Name	Description	Type
@expand	Expand transition start	() => void
@expanded	Expand transition completed	() => void
@collapse	Collapse transition start	() => void
@collapsed	Collapse transition completed	() => void

Usage

<script setup>
import { ref } from 'vue'
import { Collapse } from 'vue-collapsed'

const isExpanded = ref(false)
</script>

<template>
  <button @click="isExpanded = !isExpanded">Trigger</button>

  <Collapse :when="isExpanded">
    <p>{{ 'Collapsed '.repeat(100) }}</p>
  </Collapse>
</template>

Automatic transition (default behavior)

By default, if no height transition is specified the following one is automatically added to the Collapse element:

height var(--vc-auto-duration) cubic-bezier(0.33, 1, 0.68, 1)

--vc-auto-duration is calculated in background and corresponds to an optimal transition duration based on your content height.

This is the recommended way to use this package unless you want to customize the transition.

Custom transition

If you prefer to use a custom duration or easing, add a class to Collapse that transitions the height property:

<Collapse :when="isExpanded" class="v-collapse">
  <p>{{ 'Collapsed '.repeat(100) }}</p>
</Collapse>

.v-collapse {
  transition: height 300ms ease-out;
  /* or transition: height var(--vc-auto-duration) ease-in-out */
}

Multiple transitions

To transition other properties use the attribute data-collapse:

Transition	From	Enter	Leave
Expand	collapsed	expanding	expanded
Collapse	expanded	collapsing	collapsed

.v-collapse {
  --dur-easing: var(--vc-auto-duration) cubic-bezier(0.33, 1, 0.68, 1);
  transition:
    height var(--dur-easing),
    opacity var(--dur-easing);
}

.v-collapse[data-collapse='expanded'],
.v-collapse[data-collapse='expanding'] {
  opacity: 1;
}

.v-collapse[data-collapse='collapsed'],
.v-collapse[data-collapse='collapsing'] {
  opacity: 0;
}

Or to use different easings/durations for expand and collapse:

.v-collapse[data-collapse='expanding'] {
  transition: height 600ms ease-in-out;
}

.v-collapse[data-collapse='collapsing'] {
  transition: height 300ms ease-out;
}

Above values can also be accessed using v-slot:

<Collapse :when="isExpanded" class="v-collapse" v-slot="{ state }">
  {{ state === 'collapsing' ? 'Collapsing content...' : null }}
</Collapse>

Example - Accordion

<script setup>
import { reactive } from 'vue'
import { Collapse } from 'vue-collapsed'

const questions = reactive([
  {
    title: 'Question one',
    answer: 'Answer one',
    isExpanded: false // Initial value
  },
  {
    title: 'Question two',
    answer: 'Answer two',
    isExpanded: false
  },
  {
    title: 'Question three',
    answer: 'Answer three',
    isExpanded: false
  }
])

function handleAccordion(selectedIndex) {
  questions.forEach((_, index) => {
    questions[index].isExpanded = index === selectedIndex ? !questions[index].isExpanded : false
  })
}

/**
 * For individual control you might use:
 *
 * function handleMultiple(index) {
 *   questions[index].isExpanded = !questions[index].isExpanded
 * }
 */
</script>

<template>
  <div v-for="(question, index) in questions" :key="question.title">
    <button @click="handleAccordion(index)">
      {{ question.title }}
    </button>
    <Collapse :when="questions[index].isExpanded">
      <p>
        {{ question.answer }}
      </p>
    </Collapse>
  </div>
</template>

Accessibility

vue-collapsed automatically detects if users prefer reduced motion and will disable transitions accordingly while keeping the same API behavior (emitting events and post-transition styles).

You should only add aria attributes to the Collapse element according to your use case.

<script setup>
import { ref, computed } from 'vue'
import { Collapse } from 'vue-collapsed'

const isExpanded = ref(false)

const TOGGLE_ID = 'toggle-id'
const COLLAPSE_ID = 'collapse-id'

const toggleAttrs = computed(() => ({
  id: TOGGLE_ID,
  'aria-controls': COLLAPSE_ID,
  'aria-expanded': isExpanded.value
}))

const collapseAttrs = {
  role: 'region',
  id: COLLAPSE_ID,
  'aria-labelledby': TOGGLE_ID
}

function handleCollapse() {
  isExpanded.value = !isExpanded.value
}
</script>

<template>
  <div>
    <button v-bind="toggleAttrs" @click="handleCollapse">This a panel.</button>
    <Collapse v-bind="collapseAttrs" :when="isExpanded">
      <p>{{ 'Collapsed '.repeat(100) }}</p>
    </Collapse>
  </div>
</template>

Manually disabling transitions

<template>
  <Collapse :when="isExpanded" class="instant-collapse">
    <p>{{ 'Collapsed '.repeat(100) }}</p>
  </Collapse>
</template>

<style>
.instant-collapse {
  transition: none;
}
</style>

License

MIT