Vue Collapsed

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

💡 Requires Vue v3.0.0 or above.

Get Started

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

import { Collapse } from 'vue-collapsed'

createApp(App).component('Collapse', Collapse).mount('#app')

Or import it locally:

import { Collapse } from '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	❌
`onExpand`	Callback on expand transition start	() => void	❌
`onExpanded`	Callback on expand transition completed	() => void	❌
`onCollapse`	Callback on collapse transition start	() => void	❌
`onCollapsed`	Callback on 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">This a panel.</button>
  <Collapse :when="isExpanded" class="v-collapse">
    <p>This is a paragraph.</p>
  </Collapse>
</template>

<style>
.v-collapse {
  transition: height 300ms cubic-bezier(0.33, 1, 0.68, 1);
}
</style>

Auto Duration

Vue Collapsed automatically calculates the optimal duration according to the content height. Use it by referencing the variable --vc-auto-duration:

.v-collapse {
  transition: height var(--vc-auto-duration) ease-out;
}

💡 Use calc() to control the speed, e.g. calc(var(--vc-auto-duration) * 0.75).

💡 Find a full list of easings at easings.net.

Additional transitions/styles

To transition other properties or add granular styles 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;
}

Above values can also be accessed using v-slot:

<Collapse :when="isExpanded" class="v-collapse" v-slot="{ state }">
  {{ state === 'collapsing' ? 'Collapsing...' : 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" class="v-collapse">
      <p>
        {{ question.answer }}
      </p>
    </Collapse>
  </div>
</template>

<style>
.v-collapse {
  transition: height var(--vc-auto-duration) cubic-bezier(0.33, 1, 0.68, 1);
}
</style>

Example - Callbacks

<script setup>
// ...

const sectionsRef = ref([])

function scrollIntoView(index) {
  sectionsRef.value[index].scrollIntoView({ behavior: 'smooth' })
}
</script>

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

<style>
.v-collapse {
  transition: height var(--vc-auto-duration) cubic-bezier(0.33, 1, 0.68, 1);
}
</style>

Make it accessible

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

const isExpanded = ref(false)

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" class="v-collapse">
      <p>This is a paragraph.</p>
    </Collapse>
  </div>
</template>

<style>
.v-collapse {
  transition: height var(--vc-auto-duration) cubic-bezier(0.33, 1, 0.68, 1);
}
</style>

Credits

@roginfarrer — For the sweetest implementation of a 0 to auto height transition using requestAnimationFrame I've ever seen.

License

MIT

Alexnortung/vue-collapsed