vue 列表动画 transition-group 说明及demo

项目上需要实现一个无限向上滚动,并且不同透明度的动效,研究了一下transition-group,发现用起来确实非常方便.记录一下transition-group的使用方法.及demo源码.

transition-group 会渲染成一个真实标签,如tag="div" 渲染div标签.
给name属性赋值定义类名前缀,拿name="list"举例:

list-enter : 在元素插入的时候存在,再下一帧移除 (元素的初始状态设置)
list-enter-active : 在元素运动过程中始终存在
list-enter-to : 一开始元素插入时不存在,下一帧添加,在元素运动过程中始终存在(设置动画目标状态)
list-leave: 元素移除时立即生效,下一帧删除(元素删除的初始状态设置)
list-leave-active: 元素移除运动过程中始终存在
list-leave-to: 一开始元素移除不存在,下一帧添加(设置动画移除状态)

list-move: 非插入删除的元素都会存在

demo

<template>
  <div class="context-wrap">
    <div class="left-arrow arrow"></div>
    <transition-group v-if="items !== null" class="list" name="list" tag="div">
      <div class="list-item" v-for="item in items" :key="item.index">
        {{item.name}}
        <span style="color:#FFAD4B;">{{item.value}}</span>{{item.surfix}}
      </div>
    </transition-group>
    <div class="right-arrow arrow"></div>
  </div>
</template>
<script>
export default {

  data () {
    return {
      sourceList: createList(), // 原始数据
      delay: 3000,
      items: null,
      nextIndex: 1
    }
  },
  mounted () {
    this.items = this.copyList()
    this.time = setTimeout(this.toggleIndex, 3000);
  },
  beforeDestroy () {
    if (this.time) {
      clearTimeout(this.time)
      this.time = null
    }

  },
  methods: {
    copyList () {
      let list = this.sourceList.map(t => {
        return {
          ...t,
          index: this.nextIndex++
        }
      })
      return list
    },
    toggleIndex () {
      let item = {
        ...this.items[0],
        index: this.nextIndex++
      }
      this.items = [...this.items.splice(1, this.items.length), item]

      this.time = setTimeout(this.toggleIndex, this.delay);
    }
  }
}

function createList () {
  let list = []
  for (let i = 0; i < 5; i++) {
    let item = {
      name: '国泰君安对客户A35666556Q强平',
      surfix: '张',
      value: i + 50
    }
    list.push(item)
  }
  return list
}
</script>


<style lang="scss" scoped>
.context-wrap {
  width: 100%;
  height: 90%;
  margin-top: 5%;
  margin-left: 20px;
  display: flex;
  overflow: hidden;
  align-items: center;
  position: relative;
  .list {
    width: 286px;
    height: 280px;
    .list-item {
      margin-bottom: 15px;
      width: 280px;
      height: 40px;
      border: 1px solid #071532;
      font-size: 14px;
      color: #000;
      display: flex;
      justify-content: center;
      align-items: center;
      transition: all 3s;
      &:nth-child(1) {
        opacity: 0.2;
      }
      &:nth-child(2) {
        opacity: 0.5;
      }
      &:nth-child(3) {
        opacity: 1;
      }
      &:nth-child(4) {
        opacity: 0.5;
      }
      &:nth-child(5) {
        opacity: 0.2;
      }
      &:nth-child(6) {
        opacity: 0.2;
      }
      /** 插入过程 **/
      &.list-enter-active {
      }
      /** 移除过程 **/
      &.list-leave-active {
        position: absolute;
      }

      /*** 开始插入、移除结束的位置变化 ***/

      // 定义移除的元素目标状态
      &.list-leave-to {
        opacity: 0;
        transform: translateY(-55px);
      }

      // 定义插入的元素初始状态.
      &.list-enter {
        opacity: 0;
        transform: translateY(55px);
      }
    }

    // 覆盖上面列表元素每个位置的透明度
    .list-move {
      &:nth-child(2) {
        opacity: 0.2;
      }
      &:nth-child(3) {
        opacity: 0.5;
      }
      &:nth-child(4) {
        opacity: 1;
      }
      &:nth-child(5) {
        opacity: 0.5;
      }
    }

    /*** 元素定位改变时动画 ***/
    // .list-move {
    //   transition: all 5s;
    // }
  }
}
</style>