beforeRouteEnter(to, from, next) {
 //判斷從index頁(yè)面進(jìn)入，將list的isBack設(shè)置為true
 //這樣就可以請(qǐng)求數(shù)據(jù)了
 if (from.name == 'index') {
 to.meta.isBack = true;
 }
 next();
 },
 activated: function () {
 if (this.$route.meta.isBack || this.isFirstEnter) {
 //清理已有商品列表的數(shù)據(jù)，重新請(qǐng)求數(shù)據(jù)，如果不清除的話(huà)就會(huì)有之前的商品緩存，延遲顯示最新的商品
 this.proData = [];
 //請(qǐng)求數(shù)據(jù)
 this.fetchData();
 }
 //重新設(shè)置當(dāng)前路由的isBack
 this.$route.meta.isBack = false;
 //重新設(shè)置是否第一次進(jìn)入
 this.isFirstEnter = false;
 },
 mounted: function () {
 //如果是第一次進(jìn)入，或者刷新操作的話(huà)，也請(qǐng)求數(shù)據(jù)
 this.isFirstEnter = true;
 },

const appRouter = {
 mode: "history",
 base: "/m/",
 routes: [
 {
 path: "",
 redirect: "/index"
 },
 {
 path: "/index",
 name: "index",
 component: Index,
 meta: {
 keepAlive: true
 }
 },
 {
 path: "/list",
 name: "list",
 component: List,
 meta: {
 keepAlive: true,
 isBack: false //isback是true的時(shí)候請(qǐng)求數(shù)據(jù)，或者第一次進(jìn)入的時(shí)候請(qǐng)求數(shù)據(jù)
 }
 },
 {
 path: "/product/:id",
 name: "product",
 component: Product,
 meta: {
 keepAlive: false
 }
 }
 
 ]
};

Vue.use(Router);
export default new Router(appRouter);