How vue.js monitors routing changes

Vue.js method of monitoring route changes: 1. Implemented through watch, the code is [watch:{$route(to,from){console.log(to.path);}]; 2. key It is used to prevent "reuse", the code is [

The operating environment of this tutorial: windows10 system, vue2.9, this article is applicable to all brands of computers.

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# #vue.js method of monitoring routing changes:

Method 1: Through watch

// 监听,当路由发生变化的时候执行
watch:{
  $route(to,from){
    console.log(to.path);
  }
},

or

// 监听,当路由发生变化的时候执行
watch: {
  $route: {
    handler: function(val, oldVal){
      console.log(val);
    },
    // 深度观察监听
    deep: true
  }
},

or

// 监听,当路由发生变化的时候执行
watch: {
  '$route':'getPath'
},
methods: {
  getPath(){
    console.log(this.$route.path);
  }
}

Method 2: Key is used to prevent "reuse"

Vue provides you with a way to declare "these two elements are completely independent - don't Reuse them”. Just add a key attribute with a unique value (original words from the Vue document)

<router-view :key="key"></router-view>
 
computed: {
  key() {
    return this.$route.name !== undefined? this.$route.name +new Date(): this.$route +new Date()
  }
}

Using the computed attribute and

Date() can ensure that the key is different every time, so You can refresh the data as desired.

Method 3: Through the hook function of vue-router beforeRouteEnter beforeRouteUpdate beforeRouteLeave

<script>
  // 引入 Tabbar组件
  import mTabbar from &#39;./components/Tabbar&#39;
  import mTabbarItem from &#39;./components/TabbarItem&#39;
  // 引入 vuex 的两个方法
  import {mapGetters, mapActions} from &#39;vuex&#39;
 
  export default {
    name: &#39;app&#39;,
    // 计算属性
    computed:mapGetters([
      // 从 getters 中获取值
      &#39;tabbarShow&#39;
    ]),
    // 监听,当路由发生变化的时候执行
    watch:{
      $route(to,from){
        if(to.path == &#39;/&#39; || to.path == &#39;/Prisoner&#39; || to.path == &#39;/Goods&#39; ||
         to.path == &#39;/Time&#39; || to.path == &#39;/Mine&#39;){
          /**
           * $store来自Store对象
           * dispatch 向 actions 发起请求
           */
          this.$store.dispatch(&#39;showTabBar&#39;);
        }else{
          this.$store.dispatch(&#39;hideTabBar&#39;);
        }
      }
    },
    beforeRouteEnter (to, from, next) {
      // 在渲染该组件的对应路由被 confirm 前调用
      // 不！能！获取组件实例 `this`
      // 因为当钩子执行前，组件实例还没被创建
    },
    beforeRouteUpdate (to, from, next) {
      // 在当前路由改变，但是该组件被复用时调用
      // 举例来说，对于一个带有动态参数的路径 /foo/:id，在 /foo/1 和 /foo/2 之间跳转的时候，
      // 由于会渲染同样的 Foo 组件，因此组件实例会被复用。而这个钩子就会在这个情况下被调用。
      // 可以访问组件实例 `this`
    },
    beforeRouteLeave (to, from, next) {
      // 导航离开该组件的对应路由时调用
      // 可以访问组件实例 `this`
    },
    components:{
      mTabbar,
      mTabbarItem
    },
    data() {
      return {
        select:"Building"
      }
    }
  }
</script>

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