Vue指令的钩子函数使用方法

<div id="app">
 <my-comp v-if="msg" :msg="msg"></my-comp>
 <button @click="update">更新</button>
 <button @click="uninstall">卸载</button>
 <button @click="install">安装</button>
</div>

Vue.directive('hello', {
 bind: function (el) {
  console.log('bind')
 },
 inserted: function (el) {
  console.log('inserted')
 },
 update: function (el) {
  console.log('update')
 },
 componentUpdated: function (el) {
  console.log('componentUpdated')
 },
 unbind: function (el) {
  console.log('unbind')
 }
})
var myComp = {
 template: '<h1 v-hello>{{msg}}</h1>',
 props: {
  msg: String
 }
}
new Vue({
 el: '#app',
 data: {
  msg: 'Hello'
 },
 components: {
  myComp: myComp
 },
 methods: {
  update: function () {
   this.msg = 'Hi'
  },
  uninstall: function () {
   this.msg = ''
  },
  install: function () {
   this.msg = 'Hello'
  }
 }
})

bind: function (el) {
 console.log(el.parentNode) // null
 console.log('bind')
},
inserted: function (el) {
 console.log(el.parentNode) // <div id="app">...</div>
 console.log('inserted')
}

update: function (el) {
 console.log(el.innerHTML) // Hello
 console.log('update')
},
componentUpdated: function (el) {
 console.log(el.innerHTML) // Hi
 console.log('componentUpdated')
}

Vue.directive('hello', {
 bind: function (el, binding) {
  // 在 bind 钩子中初始化库实例
  // 如果需要使用父节点，也可以在 inserted 钩子中执行
  el.__library__ = new Library(el, binding.value)
 },
 update: function (el, binding) {
  // 模版更新意味着指令的参数可能被改变，这里可以对库实例的参数作更新
  // 酌情使用 update 或 componentUpdated 钩子
  el.__library__.setOptions(Object.assign(binding.oldValue, binding.value))
 },
 unbind: function (el) {
  // 释放实例
  el.__library__.destory()
 }
})