ant-design-vue/components/_util/openAnimation.js

import cssAnimation from './css-animation'
import raf from 'raf'

function animate (node, show, done, type) {
  let height
  let requestAnimationFrameId
  let appearRequestAnimationFrameId
  return cssAnimation(node, 'ant-motion-collapse', {
    start () {
      if (appearRequestAnimationFrameId) {
        raf.cancel(appearRequestAnimationFrameId)
      }
      if (!show) {
        node.style.height = `${node.offsetHeight}px`
        node.style.opacity = '1'
      } else {
        height = node.offsetHeight
        // not get offsetHeight when appear
        // set it into raf get correct offsetHeight
        if (height === 0) {
          appearRequestAnimationFrameId = raf(() => {
            height = node.offsetHeight
            node.style.height = '0px'
            node.style.opacity = '0'
          })
        } else {
          node.style.height = '0px'
          node.style.opacity = '0'
        }
      }
    },
    active () {
      if (requestAnimationFrameId) {
        raf.cancel(requestAnimationFrameId)
      }
      requestAnimationFrameId = raf(() => {
        node.style.height = `${show ? height : 0}px`
        node.style.opacity = show ? '1' : '0'
      })
    },
    end () {
      if (appearRequestAnimationFrameId) {
        raf.cancel(appearRequestAnimationFrameId)
      }
      if (requestAnimationFrameId) {
        raf.cancel(requestAnimationFrameId)
      }
      node.style.height = ''
      node.style.opacity = ''
      done && done()
    },
  })
}

const animation = {
  enter (node, done) {
    return animate(node, true, done)
  },
  leave (node, done) {
    return animate(node, false, done)
  },
}

export default animation