实例生命周期钩子

实例生命周期钩子API

简单理解，生命周期钩子函数就是vue实例在某一个时间点会自动执行的函数。

  <div id="app">{{msg}}</div>
  <script src="https://cdn.bootcss.com/vue/2.4.2/vue.js"></script>
  <script>
    var vm = new Vue({
      el: '#app',
      data: {
        msg: 'Vue的生命周期'
      },
      beforeCreate: function() {
        console.group('------beforeCreate创建前状态------');
        console.log("el     : " + this.$el); //undefined
        console.log("data   : " + this.$data); //undefined
        console.log("msg: " + this.msg) //undefined
      },
      created: function() {
        console.group('------created创建完毕状态------');
        console.log("el     : " + this.$el); //undefined
        console.log("data   : " + this.$data); //已被初始化
        console.log("msg: " + this.msg); //已被初始化
      },
      beforeMount: function() {
        console.group('------beforeMount挂载前状态------');
        console.log(this.$el);// <div id="app">{{msg}}</div> 挂载前状态
      },
      mounted: function() {
        console.group('------mounted 挂载结束状态------');
        console.log(this.$el);// <div id="app">Vue的生命周期</div>   msg内容被挂载并渲染到页面
      },
        // 当data被修改之前
      beforeUpdate: function () {
        console.group('beforeUpdate 更新前状态===============》');
        console.log("el     : " + this.$el);
        console.log(this.$el);
        console.log("data   : " + this.$data);
        console.log("msg: " + this.msg);
      },
        // 触发beforeUpdate之后，虚拟DOM重新渲染并应用更新
        // 当data被修改之后
      updated: function () {
        console.group('updated 更新完成状态===============》');
        console.log("el     : " + this.$el);
        console.log(this.$el);
        console.log("data   : " + this.$data);
        console.log("msg: " + this.msg);
      },
        // 调用vm.$destroy() 销毁前
      beforeDestroy: function () {
        console.group('beforeDestroy 销毁前状态===============》');
        console.log("el     : " + this.$el);
        console.log(this.$el);
        console.log("data   : " + this.$data);
        console.log("msg: " + this.msg);
      },
        // 调用vm.$destroy() 销毁后
      destroyed: function () {
        console.group('destroyed 销毁完成状态===============》');
        console.log("el     : " + this.$el);
        console.log(this.$el);
        console.log("data   : " + this.$data);
        console.log("msg: " + this.msg)
      }
    })
  </script>

Demo

See the Pen 生命周期钩子 by aths (@aths) on CodePen.

生命周期图示