vue自定义keepalive组件的问题解析

    <keep-alive exclude="a,b,c" >
        <router-view></router-view>
    </keep-alive>

function remove(arr, item) {
  if (arr.length) {
    var index = arr.indexOf(item)
    if (index > -1) {
      return arr.splice(index, 1)
    }
  }
}
function getFirstComponentChild(children) {
  if (Array.isArray(children)) {
    for (var i = 0; i < children.length; i++) {
      var c = children[i]
      if (isDef(c) && (isDef(c.componentOptions) || isAsyncPlaceholder(c))) {
        return c
      }
    }
  }
}
function isDef(v) {
  return v !== undefined && v !== null
}
function isAsyncPlaceholder(node) {
  return node.isComment && node.asyncFactory
}
var patternTypes = [String, RegExp, Array]
export default {
  name: 'keep-alive',
  abstract: true,
  computed: {
    // 这里算是一个伪代码
    // 缓存的数组 [{ 'tab1/组件名称':comp, 'tab2/组件名称':comp },{ 'tab1/组件名称':comp, 'tab2/组件名称':comp }]  
    cacheArray() {
      return this.$store.state.xxx.groupCache
    },
    // 当前选中的分组 例：0/1/2... 这里用来读取cache数组的index
    groupIndex() {
      return this.$store.state.xxx.groupIndex
    }
  },
  created: function created() {
    // 当前tab的缓存
    const cache = this.cacheArray[this.groupIndex]
    this.cache = cache || Object.create(null)
    // TODO 页面初始化事件,后续可触发初始化事件
  },
  destroyed: function destroyed(to, form) {
    // TODO 页面离开事件，后续可触发关闭事件
  },
  render: function render() {
    var slot = this.$slots.default
    var vnode = getFirstComponentChild(slot)
    var componentOptions = vnode && vnode.componentOptions
    // check pattern
    var ref$1 = this
    var cache = ref$1.cache
    const key = `${this.groupIndex}/${componentOptions.Ctor.options.name}`
    // 存在key直接读取
    if (cache[key]) {
      vnode.componentInstance = cache[key].componentInstance
    } else {
      // 没有进行缓存
      cache[key] = vnode
    }
    // 写入缓存
    this.$store.dispatch('setGroupCache', {
      cache: this.cache
    })
    return vnode || (slot && slot[0])
  }
}

<group-keep-alive>
   <router-view :key="key" />
/group-keep-alive>

// key一定要区分
computed: {
    key() {
      return `${选中index}/${fullpath}`
    },
}