vue2生命周期
1.有哪些生命周期：
beforeCreate
created
beforeMount
mounted
beforeUpdate
updated
beforeDestroy
destroyed
2.一旦进入页面或组件会执行哪些生命周期：
beforeCreate
created
beforeMount
mounted
3.在哪个阶段有$el,$data:
从created开始有$data,从mounted开始有$el.
4.如果加入keep-alive会多两个生命周期：
activated
deactivated
5.如果加入keep-alive第一次进入组件会执行哪些生命周期，第二次或者第N次进入组件会执行哪些生命周期：
第一次：
beforeCreate
created
beforeMount
mounted
activated
第二次或第N次：
activated
6.如果要改版生命周期或者el和data出现的顺序要怎么做：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=
, initial-scale=1.0">
<title>生命周期原理</title>
</head>
<script src="./vue.js"></script>
<body>
<div id="App">这是vue</div>
</body>
<script>
new vue({
el: '#App',
data() {
return {
str: '124'
}
},
beforeCreate() {
console.log(this)//这里this是这个VUE实例
console.log('beforeCreate', this.$data, this.$el)
},
Created() {
console.log('Created', this.$data, this.$el)
},
beforeMount() {
console.log('beforeMount', this.$data, this.$el)
},
mounted() {
console.log('mounted', this.$data, this.$el)
},
})
</script>
</html>
class vue {
constructor(options) {
console.log(this)//这里this是这个VUE类
options.beforeCreate.bind(this)()
this.$data = options.data
options.Created.bind(this)()
options.beforeMount.bind(this)()
this.$el = document.querySelector(options.el)
options.mounted.bind(this)()
}
}
//模拟一个vue ，vue本质上就是一个class类，里面的方法其实是在构造函数里面执行的
