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 lyc (@lyc) on CodePen.

生命周期图示