keep-alive源码笔记二-删除keep-alive缓存

1. App.vue 中保存 keep-alive 的实例

--- html ---

 
   
 
 home
 about

--- js ---
mounted() {
 // 这里要注意keep-alive在父组件中的位置，也可以通过匹配tag属性来获取keep-alive的实例
 // 也可绑定到vuex中
 window._keepAliveIns = this._vnode.children[0].componentInstance
 console.log(this._vnode.children[0].componentInstance, '_keepAliveIns ')
}

也可以通过匹配tag属性来获取keep-alive的实例

2. 在组件中删除缓存

--- component ---

  del

--- js ---
del() {
  // 删除所有缓存
  // window._keepAliveIns.cache = {}
  // window._keepAliveIns.keys.length = 0
  
  // 删除某个缓存
  // 获取当前组件的name，也可以指定其他组件的name
  const currKey = this._vnode.context.$options.name
  const cache = window._keepAliveIns.cache
  const targetEntry = Object.entries(cache).find(([key, value]) => {
    return value && (value.name == currKey )
  })
  if(targetEntry) {
    const keys = window._keepAliveIns.keys
    const delKey = targetEntry[0]
    this.pruneCacheEntry(cache, delKey, keys, this._vnode)
  }
},

// pruneCacheEntry，remove 是源码中删除缓存的方法
pruneCacheEntry (cache, key, keys, current) {
  const entry = cache[key]
  if (entry && (!current || entry.tag !== current.tag)) {
    entry.componentInstance.$destroy()
  }
  cache[key] = null
  this.remove(keys, key)
},
remove (arr, item) {
  if (arr.length) {
    const index = arr.indexOf(item)
    if (index > -1) {
      return arr.splice(index, 1)
    }
  }
}