Vue实例的生命周期（钩子函数）

var app=new Vue({
el:'#app',
beforeCreate:function(){
console.log('1-beforeCreate 初始化之后');
},
created:function(){
console.log('2-created 创建完成');
},
beforeMount:function(){
console.log('3-beforeMount 挂载之前');
},
mounted:function(){
console.log('4-mounted 被创建');
},
beforeUpdate:function(){
console.log('5-beforeUpdate 数据更新前');
},
updated:function(){
console.log('6-updated 被更新后');
},
activated:function(){
console.log('7-"keep-alive"中组件被激活时');
},
deactivated:function(){
console.log('8-"keep-alive"中组件被停用时');
},
beforeDestroy:function(){
console.log('9-beforeDestroy 销毁之前');
},
destroyed:function(){
console.log('10-destroyed 销毁之后')
}
})

activated和deactivated上面的图没有，这个时vue的<keep-alive></keep-alive>才能触发钩子，而keep-alive是保存组件内部状态的一种做法

而keep-alive的基本使用方法也简单：

<keep-alive>
<router-view></router-view>
</keep-alive>