在不使用keep-alive时，通过路由跳转到另一组件上时，上一个组件会被vue销毁，在次进入，页面会保持初始状态，不会对用户的更改保留，如果需要包作在某组件上的更改，就可以使用keep-alive保存路由入口
<keep-alive>
<router-view></router-view>
</keep-alive>
<body>
<div id="app"></div>
<script>
let One = {
template: `<div>
<h1 @click="changeColor">One</h1>
</div>`,
methods: {
changeColor(e) {
e.target.style.color = 'green';
}
},
created() {
console.log("One-created");
},
mounted() {
console.log("One-mounted");
},
destroyed() {
console.log('One-destroyed');
//使用了keep-alive 组件不再销毁，所以这条不会打印，不用keep-alive会显示这条调试，也就是说使用keep-alive组件缓存了不会销毁，这种实现视需求而定，是否要再返回某一页面时在页面上做出的更改保留
}
};
let Two = {
template: `<div>
<h1>Two</h1>
</div>`,
created() {
console.log("Two-created");
},
mounted() {
console.log("Two-mounted");
},
destroyed() {
console.log('Two-destroyed');
}
};
let App = {
template: `<div id="app">
<router-link :to="{name:'One'}">One</router-link>
<router-link :to="{name:'Two'}">Two</router-link>
<keep-alive>
<router-view></router-view>
</keep-alive>
</div>`
};
Vue.use(VueRouter);
let router = new VueRouter({
routes: [
{
name: 'One',
path: '/one',
component: One
},
{
name: 'Two',
path: '/two',
component: Two
}
]
});
let vm = new Vue({
el: "#app",
components: {
App
},
template: `<App></App>`,
router
})
</script>
</body>