10、路由（router、localStorage、导航守卫forEach）

<template>
  <div>
    <form @submit.prevent="doLogin">
      <input type="text" v-model="username" />
      <button>提交</button>
    </form>
  </div>
</template>
<script>
export default {
  data() {
    return {
      username: "",
    };
  },
  methods: {
    doLogin() {
      console.log(this.username);
      // 本地存储(浏览器)
      localStorage.setItem("username", this.username);
      // 页面跳转
      this.$router.push("/");
    },
  },
};
</script>

<template>
  <div id="app">
    <nav>
      <!-- 相当于a标签：href -->
      <router-link to="/">首页</router-link> |
      <router-link to="/blog">博客</router-link>|
      <router-link to="/picture">图片</router-link>|
      <router-link to="/login">登陆</router-link>
      <div v-if="username">
        <span>欢迎:{{ username }}</span>
        <button @click="logout">退出</button>
      </div>
    </nav>
    <router-view />
  </div>
</template>
<script>
export default {
  watch: {
    // 监听路由切换:刷新用户名
    "$route.path": function () {
      this.username = localStorage.getItem("username");
    },
  },
  data() {
    return {
      // 获取存储
      username: localStorage.getItem("username"),
    };
  },
  methods: {
    logout() {
      // 清除本地存储(浏览器)
      localStorage.clear();
      // 跳转页面
      this.$router.push("/login");
    },
  },
};
</script>
<style></style>

// 导航守卫:
router.beforeEach((to, from, next) => {
  if (to.path !== "/login") {
    if (localStorage.getItem("username")) {
      next();
    } else {
      next("/login");
    }
  }
  next();
})