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

Emits

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:

.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