Vue 组件通讯传值（父子组件通讯/兄弟组件通讯/跨级通讯）

// 父组件
<template>
  <div id="app">
    <users v-bind:users="users"></users>//前者自定义名称便于子组件调用，后者要传递数据名
  </div>
</template>
<script>
import Users from "./components/Users"
export default {
  name: ‘App‘,
  data(){
    return{
      users:["Henry","Bucky","Emily"]
    }
  },
  components:{
    "users":Users
  }
}

// 子组件
<template>
  <div class="hello">
    <ul>
      <li v-for="user in users">{{user}}</li>//遍历传递过来的值，然后呈现到页面
    </ul>
  </div>
</template>
<script>
export default {
  name: ‘HelloWorld‘,
  props:{
    users:{           //这个就是父组件中子标签自定义名字
      type:Array,
      required:true
    }
  }
}
</script>

// 子组件
<template>
  <header>
    <h1 @click="changeTitle">{{title}}</h1>//绑定一个点击事件
  </header>
</template>
<script>
export default {
  name: ‘app-header‘,
  data() {
    return {
      title:"Vue.js Demo"
    }
  },
  methods:{
    changeTitle() {
      this.$emit("titleChanged","子向父组件传值");//自定义事件  传递值“子向父组件传值”
    }
  }
}
</script>

// 父组件
<template>
  <div id="app">
    <app-header v-on:titleChanged="updateTitle" ></app-header>//与子组件titleChanged自定义事件保持一致
   // updateTitle($event)接受传递过来的文字
    <h2>{{title}}</h2>
  </div>
</template>
<script>
import Header from "./components/Header"
export default {
  name: ‘App‘,
  data(){
    return{
      title:"传递的是一个值"
    }
  },
  methods:{
    updateTitle(e){   //声明这个函数
      this.title = e;
    }
  },
  components:{
   "app-header":Header,
  }
}
</script>

var Event=new Vue();
    Event.$emit(事件名,数据);
    Event.$on(事件名,data => {});

<div id="itany">
    <my-a></my-a>
    <my-b></my-b>
    <my-c></my-c>
</div>
<template id="a">
  <div>
    <h3>A组件：{{name}}</h3>
    <button @click="send">将数据发送给C组件</button>
  </div>
</template>
<template id="b">
  <div>
    <h3>B组件：{{age}}</h3>
    <button @click="send">将数组发送给C组件</button>
  </div>
</template>
<template id="c">
  <div>
    <h3>C组件：{{name}}，{{age}}</h3>
  </div>
</template>
<script>
var Event = new Vue();//定义一个空的Vue实例
var A = {
    template: ‘#a‘,
    data() {
      return {
        name: ‘tom‘
      }
    },
    methods: {
      send() {
        Event.$emit(‘data-a‘, this.name);
      }
    }
}
var B = {
    template: ‘#b‘,
    data() {
      return {
        age: 20
      }
    },
    methods: {
      send() {
        Event.$emit(‘data-b‘, this.age);
      }
    }
}
var C = {
    template: ‘#c‘,
    data() {
      return {
        name: ‘‘,
        age: ""
      }
    },
    mounted() {//在模板编译完成后执行
     Event.$on(‘data-a‘,name => {
         this.name = name;//箭头函数内部不会产生新的this，这边如果不用=>,this指代Event
     })
     Event.$on(‘data-b‘,age => {
         this.age = age;
     })
    }
}
var vm = new Vue({
    el: ‘#itany‘,
    components: {
      ‘my-a‘: A,
      ‘my-b‘: B,
      ‘my-c‘: C
    }
});    
</script>

// 父组件获取子组件值
// 父组件
this.msg2=this.$children[0].msg

// 父组件
<template>
  <component-a ref="comA"></component-a>
</template>
<script>
  export default {
    mounted () {
      const comA = this.$refs.comA;
      console.log(comA.title);  // Vue.js
      comA.sayHello();  // 弹窗
    }
  }
</script>

// 子组件
export default {
  data () {
    return {
      title: ‘Vue.js‘
    }
  },
  methods: {
    sayHello () {
      window.alert(‘Hello‘);
    }
  }
}

<component-a></component-a>
<component-b></component-b>
<component-b></component-b>

// index.vue
<template>
  <div>
    <h2>浪里行舟</h2>
    <child-com1
      :foo="foo"
      :boo="boo"
      :coo="coo"
      :doo="doo"
      title="前端工匠"
    ></child-com1>
  </div>
</template>
<script>
const childCom1 = () => import("./childCom1.vue");
export default {
  components: { childCom1 },
  data() {
    return {
      foo: "Javascript",
      boo: "Html",
      coo: "CSS",
      doo: "Vue"
    };
  }
};
</script>

// childCom1.vue
<template class="border">
  <div>
    <p>foo: {{ foo }}</p>
    <p>childCom1的$attrs: {{ $attrs }}</p>
    <child-com2 v-bind="$attrs"></child-com2>
  </div>
</template>
<script>
const childCom2 = () => import("./childCom2.vue");
export default {
  components: {
    childCom2
  },
  inheritAttrs: false, // 可以关闭自动挂载到组件根元素上的没有在props声明的属性
  props: {
    foo: String // foo作为props属性绑定
  },
  created() {
    console.log(this.$attrs); // { "boo": "Html", "coo": "CSS", "doo": "Vue", "title": "前端工匠" }
  }
};
</script>

// childCom2.vue
<template>
  <div class="border">
    <p>boo: {{ boo }}</p>
    <p>childCom2: {{ $attrs }}</p>
    <child-com3 v-bind="$attrs"></child-com3>
  </div>
</template>
<script>
const childCom3 = () => import("./childCom3.vue");
export default {
  components: {
    childCom3
  },
  inheritAttrs: false,
  props: {
    boo: String
  },
  created() {
    console.log(this.$attrs); // {"coo": "CSS", "doo": "Vue", "title": "前端工匠" }
  }
};
</script>

// childCom3.vue
<template>
  <div class="border">
    <p>childCom3: {{ $attrs }}</p>
  </div>
</template>
<script>
export default {
  props: {
    coo: String,
    title: String
  }
};
</script>

// A.vue
export default {
  provide: {
    name: ‘你好‘
  }
}

// B.vue
export default {
  inject: [‘name‘],
  mounted () {
    console.log(this.name);  // 你好
  }
}

// A 组件 
<div>
      <h1>A 组件</h1>
      <button @click="() => changeColor()">改变color</button>
      <ChildrenB />
      <ChildrenC />
</div>
......
  data() {
    return {
      color: "blue"
    };
  },
  // provide() {
  //   return {
  //     theme: {
  //       color: this.color //这种方式绑定的数据并不是可响应的
  //     } // 即A组件的color变化后，组件D、E、F不会跟着变
  //   };
  // },
  provide() {
    return {
      theme: this//方法一：提供祖先组件的实例
    };
  },
  methods: {
    changeColor(color) {
      if (color) {
        this.color = color;
      } else {
        this.color = this.color === "blue" ? "red" : "blue";
      }
    }
  }
  // 方法二:使用2.6最新API Vue.observable 优化响应式 provide
  // provide() {
  //   this.theme = Vue.observable({
  //     color: "blue"
  //   });
  //   return {
  //     theme: this.theme
  //   };
  // },
  // methods: {
  //   changeColor(color) {
  //     if (color) {
  //       this.theme.color = color;
  //     } else {
  //       this.theme.color = this.theme.color === "blue" ? "red" : "blue";
  //     }
  //   }
  // }

// F 组件 
<template functional>
  <div class="border2">
    <h3 :style="{ color: injections.theme.color }">F 组件</h3>
  </div>
</template>
<script>
export default {
  inject: {
    theme: {
      //函数式组件取值不一样
      default: () => ({})
    }
  }
};
</script>

let defaultCity = "上海"
try {   // 用户关闭了本地存储功能，此时在外层加个try...catch
  if (!defaultCity){
    defaultCity = JSON.parse(window.localStorage.getItem(‘defaultCity‘))
  }
}catch(e){}
export default new Vuex.Store({
  state: {
    city: defaultCity
  },
  mutations: {
    changeCity(state, city) {
      state.city = city
      try {
      window.localStorage.setItem(‘defaultCity‘, JSON.stringify(state.city));
      // 数据改变的时候把数据拷贝一份保存到localStorage里面
      } catch (e) {}
    }
  }
})

JSON.stringify(state.subscribeList);   // array -> string
JSON.parse(window.localStorage.getItem("subscribeList"));    // string -> array