103 lines
3.5 KiB
Markdown
103 lines
3.5 KiB
Markdown
---
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title: 生命周期
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date: 2020-02-04 15:06:59
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permalink: /pages/176808a1b5f843b8
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categories:
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- 《Vue》笔记
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- 基础
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tags:
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- Vue
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author:
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name: xugaoyi
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link: https://github.com/xugaoyi
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---
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# 实例生命周期钩子
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[实例生命周期钩子API](https://cn.vuejs.org/v2/guide/instance.html#实例生命周期钩子)
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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。
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<!-- more -->
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```html
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<div id="app">{{msg}}</div>
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<script src="https://cdn.bootcss.com/vue/2.4.2/vue.js"></script>
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<script>
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var vm = new Vue({
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el: '#app',
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data: {
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msg: 'Vue的生命周期'
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},
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beforeCreate: function() {
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console.group('------beforeCreate创建前状态------');
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console.log("el : " + this.$el); //undefined
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console.log("data : " + this.$data); //undefined
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console.log("msg: " + this.msg) //undefined
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},
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created: function() {
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console.group('------created创建完毕状态------');
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console.log("el : " + this.$el); //undefined
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console.log("data : " + this.$data); //已被初始化
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console.log("msg: " + this.msg); //已被初始化
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},
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beforeMount: function() {
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console.group('------beforeMount挂载前状态------');
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console.log(this.$el);// <div id="app">{{msg}}</div> 挂载前状态
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},
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mounted: function() {
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console.group('------mounted 挂载结束状态------');
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console.log(this.$el);// <div id="app">Vue的生命周期</div> msg内容被挂载并渲染到页面
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},
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// 当data被修改之前
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beforeUpdate: function () {
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console.group('beforeUpdate 更新前状态===============》');
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console.log("el : " + this.$el);
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console.log(this.$el);
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console.log("data : " + this.$data);
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console.log("msg: " + this.msg);
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},
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// 触发beforeUpdate之后，虚拟DOM重新渲染并应用更新
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// 当data被修改之后
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updated: function () {
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console.group('updated 更新完成状态===============》');
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console.log("el : " + this.$el);
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console.log(this.$el);
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console.log("data : " + this.$data);
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console.log("msg: " + this.msg);
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},
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// 调用vm.$destroy() 销毁前
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beforeDestroy: function () {
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console.group('beforeDestroy 销毁前状态===============》');
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console.log("el : " + this.$el);
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console.log(this.$el);
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console.log("data : " + this.$data);
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console.log("msg: " + this.msg);
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},
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// 调用vm.$destroy() 销毁后
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destroyed: function () {
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console.group('destroyed 销毁完成状态===============》');
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console.log("el : " + this.$el);
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console.log(this.$el);
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console.log("data : " + this.$data);
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console.log("msg: " + this.msg)
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}
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})
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</script>
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```
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## Demo
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<p class="codepen" data-height="265" data-theme-id="light" data-default-tab="js,result" data-user="xugaoyi" data-slug-hash="GRJZWjb" style="height: 265px; box-sizing: border-box; display: flex; align-items: center; justify-content: center; border: 2px solid; margin: 1em 0; padding: 1em;" data-pen-title="生命周期钩子">
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<span>See the Pen <a href="https://codepen.io/xugaoyi/pen/GRJZWjb">
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生命周期钩子</a> by xugaoyi (<a href="https://codepen.io/xugaoyi">@xugaoyi</a>)
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on <a href="https://codepen.io">CodePen</a>.</span>
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</p>
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<script async src="https://static.codepen.io/assets/embed/ei.js"></script>
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## 生命周期图示
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