[JavaScript知识库] Vue3 生命周期

开发: C++知识库 Java知识库 JavaScript Python PHP知识库人工智能区块链大数据移动开发嵌入式开发工具数据结构与算法开发测试游戏开发网络协议系统运维
教程: HTML教程 CSS教程 JavaScript教程 Go语言教程 JQuery教程 VUE教程 VUE3教程 Bootstrap教程 SQL数据库教程 C语言教程 C++教程 Java教程 Python教程 Python3教程 C#教程
数码: 电脑笔记本显卡显示器固态硬盘硬盘耳机手机 iphone vivo oppo 小米华为单反装机图拉丁

-> JavaScript知识库 -> Vue3 生命周期 -> 正文阅读

[JavaScript知识库]Vue3 生命周期

复制 => 运行 => 查看结果

<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>vue生命周期学习</title>
  <script src="https://unpkg.com/vue@3"></script>
</head>

<body>
  <div id="app">
    <h1>{{message}}</h1>
  </div>
</body>
<script>
  const { createApp } = Vue
  var app = createApp({
    data() {
      return {
        message: 'Vue的生命周期'
      }
    },
    beforeCreate: function () {
      console.group('------beforeCreate创建前状态------');
      console.log("%c%s", "color:red", "el     : " + this.$el); //undefined
      console.log("%c%s", "color:red", "data   : " + JSON.stringify(this.$data));
      console.log("%c%s", "color:red", "message: " + this.message)
    },
    created: function () {
      console.group('------created创建完毕状态------');
      console.log("%c%s", "color:red", "el     : " + this.$el);
      console.log("%c%s", "color:red", "data   : " + JSON.stringify(this.$data));
      console.log("%c%s", "color:red", "message: " + this.message); 
    },
    beforeMount: function () {
      console.group('------beforeMount挂载前状态------');
      console.log("%c%s", "color:red", "el     : " + (this.$el));
      console.log('el 为', this.$el);
    },
    mounted: function () {
      console.group('------mounted 挂载结束状态------');
      console.log("%c%s", "color:red", "el     : " + this.$el); 
      console.log('el 为', this.$el);
    },
  })
  app.mount('#app')
</script>

</html>

在这里插入图片描述

%c 给输出指定颜色, 比如

var str = "%c hello %c world";
var arg1 = "color: #fadfa3; background: #030307; padding:5px 0;";
var arg2 = "background: pink; padding:5px 0;";
console.log(str, arg1, arg2)

applyOptions 中执行 beforeCreate, created

beforeCreate

if (options.beforeCreate) {
  callHook(options.beforeCreate, instance, LifecycleHooks.BEFORE_CREATE)
}

中间执行函数: 给 vue instance 挂载 options , 使其有 data 之类的

created 此时 instance 中挂载了 data 等 options

if (created) {
  callHook(created, instance, LifecycleHooks.CREATED)
}

componentUpdateFn 中执行 beforeMount, mounted

beforeMount

if (bm) {
  invokeArrayFns(bm)
}

中间执行: patch(null, sunTree) => processElement => el = vnode.el = hostCreateElement(vnode.type) 给 vnode 添加 el

mounted 此时 $el 上已存在值了

if (m) {
  queuePostRenderEffect(m, parentSuspense)
}

更新函数逻辑

const componentUpdateFn = () => {
	if (!instance.isMounted) {
		if (bm) {
		  invokeArrayFns(bm)
		}
		patch(null, sunTree)
		if (m) {
		  queuePostRenderEffect(m, parentSuspense)
		}
	} else {
	   if (bu) {
	     invokeArrayFns(bu)
	   }
	   patch(prevTree, nextTree)
	   if (u) {
	     queuePostRenderEffect(u, parentSuspense)
	   }
	}
}