轉載於：https://www.cnblogs.com/xiaobaibubai/p/8383952.html
前言：
鉤子就好像是把人的出生到死亡分成一個個階段，你肯定是在出生階段起名字，而不會在成年或者死亡的階段去起名字。或者說你想在出生階段去約炮，也是不行的。組件也是一樣，每個階段它的內部構造是不一樣的。所以一般特定的鉤子做特定的事，比如ajax獲取數據就可以在mounted階段。
一、vue生命週期簡介
咱們從上圖可以很明顯的看出現在vue2.0都包括了哪些生命週期的函數了，總結一下，對官方文檔的那張圖簡化一下，就得到了這張圖。
二、生命週期探究
對於執行順序和什麼時候執行，看上面圖基本有個瞭解了。下面我們將結合代碼去看看鉤子函數的執行。
<!DOCTYPE html>
<html>
<head>
<title>鉤子函數</title>
<script type="text/javascript" src="vue_2.2.4.js"></script>
<body>
<div id="app">
<p>{{ message }}</p>
<input type="button" @click="change" value="更新數據" />
<input type="button" @click="destroy" value="銷燬" />
</div>
<script type="text/javascript">
var vm = new Vue({
el: '#app',
data: {
message : "Welcome Vue"
},
methods:{
change() {
this.message = 'Datura is me';
},
destroy() {
vm.$destroy();
}
},
beforeCreate: function () {
console.group('beforeCreate 創建前狀態===============》');
console.log("%c%s", "color:red","el : " + this.$el); //undefined
console.log("%c%s", "color:red","data : " + this.$data); //undefined
console.log("%c%s", "color:red","message: " + this.message);//undefined
},
created: function () {
console.group('created 創建完畢狀態===============》');
console.log("%c%s", "color:red","el : " + this.$el); //undefined
console.log("%c%s", "color:green","data : " + this.$data); //[object Object] => 已被初始化
console.log("%c%s", "color:green","message: " + this.message); //Welcome Vue => 已被初始化
},
beforeMount: function () {
console.group('beforeMount 掛載前狀態===============》');
console.log("%c%s", "color:green","el : " + (this.$el)); //已被初始化
console.log(this.$el); // 當前掛在的元素
console.log("%c%s", "color:green","data : " + this.$data); //已被初始化
console.log("%c%s", "color:green","message: " + this.message); //已被初始化
},
mounted: function () {
console.group('mounted 掛載結束狀態===============》');
console.log("%c%s", "color:green","el : " + this.$el); //已被初始化
console.log(this.$el);
console.log("%c%s", "color:green","data : " + this.$data); //已被初始化
console.log("%c%s", "color:green","message: " + this.message); //已被初始化
},
beforeUpdate: function () {
alert("更新前狀態");
console.group('beforeUpdate 更新前狀態===============》'); //這裏指的是頁面渲染新數據之前
console.log("%c%s", "color:green","el : " + this.$el);
console.log(this.$el);
console.log("%c%s", "color:green","data : " + this.$data);
console.log("%c%s", "color:green","message: " + this.message);
alert("更新前狀態2");
},
updated: function () {
console.group('updated 更新完成狀態===============》');
console.log("%c%s", "color:green","el : " + this.$el);
console.log(this.$el);
console.log("%c%s", "color:green","data : " + this.$data);
console.log("%c%s", "color:green","message: " + this.message);
},
beforeDestroy: function () {
console.group('beforeDestroy 銷燬前狀態===============》');
console.log("%c%s", "color:red","el : " + this.$el);
console.log(this.$el);
console.log("%c%s", "color:red","data : " + this.$data);
console.log("%c%s", "color:red","message: " + this.message);
},
destroyed: function () {
console.group('destroyed 銷燬完成狀態===============》');
console.log("%c%s", "color:red","el : " + this.$el);
console.log(this.$el);
console.log("%c%s", "color:red","data : " + this.$data);
console.log("%c%s", "color:red","message: " + this.message)
}
})
</script>
</body>
</html>