Summarize and share the various ways to implement communication between components in Vue, so you won't be afraid of interviews anymore!-Vue.js-php.cn

Interviewer: How many ways do you have to implement communication between Vue components? The following article will summarize and share with you several ways to implement communication between Vue components. You will no longer be afraid of interviews. I hope it will be helpful to you! Summarize and share the various ways to implement communication between components in Vue, so you won't be afraid of interviews anymore!

Componentization is one of the important ideas of the Vue framework. Before the front-end framework appeared, usually a website page was just a file. If a page had any data required For everyone, just declare a global variable directly. However, after the emergence of the Vue framework, a page was componentized, which meant that a page was divided into many files. Then the sharing of data between components became a big problem. Of course, Vue provides a lot for realizing data sharing between components. methods, today we will sort out what methods are there? (Learning video sharing: vuejs tutorial) Because there are only a few commonly used in projects, many friends often fail to explain everything during interviews, so it is recommended to sort it out. .

1. Which scenarios require communication?

Since all components of Vue are in the form of a component tree, there are many situations of communication between components, roughly as follows:

Communication between parent and child components
Communication between sibling components
Communication between generation-separated components
Communication between unrelated components

The recommended communication methods in each scenario are different and need to be Choose the most appropriate communication method between components according to different scenarios.

2.props and $emit

This method is usually used to transfer values between parent and child components. The parent component passes the value to the child component through attributes, and the child component passes props. take over. Child components pass data to parent components through events. Initialization project: We created the simplest Vue project and built 3 components respectively: parent, child1, child2, and then introduced them in APP.vue parent component. Two subcomponents, child1 and child2, are introduced into the parent component. The initial running interface is as follows: Summarize and share the various ways to implement communication between components in Vue, so you wont be afraid of interviews anymore!

2.1 Parent component passes value to child Component

Next we use attributes to pass values from the parent component to the child component. Parent component sample code:

// src/views/parent.vue
<template>
  <div class="parent-box">
    <p>父级组件</p>
    <div>
      <button @click="changeMsg">更改数据</button>
    </div>
    <child1 :msg="msg"></child1>
    <child2 :msg="msg"></child2>
  </div>
</template>
<script>
import child1 from "./child1.vue";
import child2 from "./child2.vue";
export default {
  data() {
    return {
      msg: "我是父组件的数据",
    };
  },
  components: {
    child1,
    child2,
  },
  methods: {
    // 点击按钮更改数据
    changeMsg() {
      this.msg = "变成小猪课堂";
    },
  },
};
</script>

Copy after login

We pass the msg in the parent component to the child component through: msg="msg", and when the button is clicked Will modify the msg in the parent component. Subcomponent sample code:

// src/views/child1.vue
<template>
  <div class="child-1">
    <p>child1组件</p>
    <div>
      <p>parent组件数据：{{ msg }}</p>
    </div>
  </div>
</template>
<script>
export default {
  props: {
    msg: {
      type: String,
      default: "",
    },
  },
};
</script>

Copy after login

The subcomponent receives data from the parent component through the props attribute. Output result:

#When we click the button, the data of the parent component changes, and the data received by the child component also changes. Then something changed. Note: :msg="msg" The msg received is a variable. You can refer to the usage principle of bind. If you do not add:, the received msg is a string.

2.2 Subcomponent passes value to parent component

Subcomponent can pass value to parent component through $emit custom event, and parent component needs to listen This event is used to receive the value passed by the subcomponent. Parent component sample code:

// src/views/parent.vue
<template>
  <div class="parent-box">
    <p>父级组件</p>
    <div>
      <button @click="changeMsg">更改数据</button>
    </div>
    <div>子组件数据：{{ childData }}</div>
    <child1 :msg="msg" @childData="childData"></child1>
    <child2 :msg="msg"></child2>
  </div>
</template>
<script>
import child1 from "./child1.vue";
import child2 from "./child2.vue";
export default {
  data() {
    return {
      msg: "我是父组件的数据",
      childData: "",
    };
  },
  components: {
    child1,
    child2,
  },
  methods: {
    changeMsg() {
      this.msg = "变成小猪课堂";
    },
    // 监听子组件事件
    childData(data) {
      this.childData = data;
    },
  },
};
</script>

Copy after login

Child component sample code:

// src/views/child1.vue
<template>
  <div class="child-1">
    <p>child1组件</p>
    <div>
      <button @click="sendData">传递数据给父组件</button>
    </div>
    <div>
      <p>parent组件数据：{{ msg }}</p>
    </div>
  </div>
</template>
<script>
export default {
  props: {
    msg: {
      type: String,
      default: "",
    },
  },
  methods: {
    // 点击按钮，使用$emit向父组件传递数据
    sendData() {
      this.$emit("childData", "我是子组件数据");
    },
  },
};
</script>

Copy after login

Output result:

We listen to the childData event in the parent component through @childData="getChildData" to obtain the data passed by the child component, which is triggered by clicking the button in the child component The $emit event passes data to the parent component. When we click the button "Pass data to parent component", the parent component can obtain the data.

3.$parent obtains the value of the parent component

This method allows the child component to obtain the value of the parent component very conveniently, including not only data, but also methods. Subcomponent sample code:

// src/views/child1.vue
<template>
  <div class="child-1">
    <p>child1组件</p>
    <div>
      <button @click="sendData">传递数据给父组件</button>
    </div>
    <div>
      <button @click="getParentData">使用$parent</button>
    </div>
    <div>
      <p>parent组件数据：{{ msg }}</p>
    </div>
  </div>
</template>
<script>
export default {
  props: {
    msg: {
      type: String,
      default: "",
    },
  },
  methods: {
    sendData() {
      this.$emit("childData", "我是子组件数据");
    },
    // 通过$parent方式获取父组件值
    getParentData() {
      console.log("父组件", this.$parent);
    },
  },
};
</script>

Copy after login

点击“使用

parent”按钮时，通过

parent获取父组件的属性或数据。

输出结果：

我们可以看到控制台打印出了父组件的所有属性，不仅仅包含了data数据，还有里面定义的一些方法等。

4.`$children`和`$refs`获取子组件值

这两种方式和$parent非常的类似，它们可以直接获取子组件的相关属性或方法，不仅限于数据。

父组件示例代码：

// src/views/parent.vue
<template>
  <div class="parent-box">
    <p>父级组件</p>
    <div>
      <button @click="changeMsg">更改数据</button>
    </div>
    <div>
      <button @click="getChildByRef">使用$children和$refs</button>
    </div>
    <div>子组件数据：{{ childData }}</div>
    <child1 ref="child1" :msg="msg" @childData="getChildData"></child1>
    <child2 :msg="msg"></child2>
  </div>
</template>
<script>
import child1 from "./child1.vue";
import child2 from "./child2.vue";
export default {
  data() {
    return {
      msg: "我是父组件的数据",
      childData: "",
    };
  },
  components: {
    child1,
    child2,
  },
  methods: {
    changeMsg() {
      this.msg = "变成小猪课堂";
    },
    // 监听子组件的自定义事件
    getChildData(data) {
      this.childData = data;
    },
    // 使用$chilren和$refs获取子组件
    getChildByRef() {
      console.log("使用$children", this.$children);
      console.log("使用$refs", this.$refs.child1);
    },
  },
};
</script>

Copy after login

输出结果：

上段代码中，我们点击按钮，分别通过 $children和$ refs的方式获取到了子组件，从而拿到子组件数据。需要注意的是， $children会返回当前组件所包含的所有子组件数组，使用$ refs时，需要在子组件上添加ref属性，有点类似于直接获取DOM节点的操作。

5. Use `$attrs` and `$listeners`

$attrs is newly proposed after Vue2.4.0, usually in multiple Used when layer components pass data. If many friends encounter a multi-layer component data transfer scenario, they may directly choose Vuex for transfer. However, if the data we need to transfer does not involve data updates and modifications, it is recommended to use the $arrts method. After all, Vuex is still Heavier.

Official website explanation:

Contains attribute bindings (except class and style) that are not recognized (and obtained) as props in the parent scope. When a component does not declare any props, all parent scope bindings (except class and style) will be included here, and internal components can be passed in via v-bind="$attrs" - when creating high-level components very useful.

The explanation on the official website is still difficult to understand. We can explain it in more popular terms.

Popular explanation:

When the parent component passes a lot of data to the child component, and the child component does not declare props to receive it, then the child component $##a t t r s The attribute contains all the data passed by the parent component (Except already p r o p s declared), sub-components can also use v − b i n d = " The attrs attribute contains all data from the parent component (except those declared by props). Sub-components can also use v-bind="$

说的再多可能还是没有代码来得简单易懂，我们新建一个孙子组件child1-child.vue，编写之后界面如下：

5.1 $attrs的使用

我们在parent父组件中多传一点数据给child1组件。

parent组件示例代码：

// src/views/parent.vue
<template>
  <div class="parent-box">
    <p>父级组件</p>
    <child1
      ref="child1"
      :msg="msg"
      :msg1="msg1"
      :msg2="msg2"
      :msg3="msg3"
      :msg4="msg4"
      @childData="getChildData"
    ></child1>
  </div>
</template>
<script>
import child1 from "./child1.vue";
import child2 from "./child2.vue";
export default {
  data() {
    return {
      msg: "我是父组件的数据",
      msg1: "parent数据1",
      msg2: "parent数据2",
      msg3: "parent数据3",
      msg4: "parent数据4",
      childData: "",
    };
  },
  components: {
    child1,
    child2,
  }
};
</script>

Copy after login

这里我们删除了一些本节用不到的代码，大家需要注意一下。

child1组件示例代码：

// src/views/child1.vue
<template>
  <div class="child-1">
    <p>child1组件</p>
    <!-- 子组件child1-child -->
    <child1-child v-bind="$attrs"></child1-child>
  </div>
</template>
<script>
import Child1Child from "./child1-child";
export default {
  components: {
    Child1Child,
  },
  props: {
    msg: {
      type: String,
      default: "",
    },
  },
  mounted() {
    console.log("child1组件获取$attrs", this.$attrs);
  }
};
</script>

Copy after login

输出结果：

上段代码中我们的parent父组件传递了5个数据给子组件：msg、msg1、msg2、msg3、msg4。但是在子组件中的props属性里面，我们只接收了msg。然后我们在子组件mounted中打印了$attrs，发现恰好少了props接收过的msg数据。

当我们在child1组件中使用 $attrs接收了组件后，可以使用v-bind="$ attrs"的形式在传递给它的子组件child1-child，上段代码中我们已经加上了v-bind。

child1-child组件示例代码：

// src/views/child1-child.vue
<template>
  <div class="child1-child">
    <p>我是孙子组件child1-child</p>
  </div>
</template>
<script>
export default {
  props: {
    msg1: {
      type: String,
      default: "",
    },
  },
  mounted() {
    console.log("child1-child组件$attrs", this.$attrs);
  },
};
</script>

Copy after login

输出结果：

我们发现child1-child组件中打印的$attrs中少了msg1，因为我们已经在props中接收了msg1。

5.2 $listeners 的使用

$listeners属性和$ attrs属性和类型，只是它们传递的东西不一样。

官网的解释：

包含了父作用域中的 (不含 .native 修饰器的) v-on 事件监听器。它可以通过 v-on="$listeners" 传入内部组件——在创建更高层次的组件时非常有用。

通俗的解释：

当父组件在子组件上定义了一些自定义的非原生事件时，在子组件内部可以通过$listeners属性获取到这些自定义事件。

它和 $attrs的区别很明显，$ attrs用来传递属性，$listeners用来传递非原生事件，我们在child1组件中打印一下看看。

child1组件示例代码：

// src/views/child1.vue
mounted() {
  console.log("child1组件获取$attrs", this.$attrs);
  console.log("child1组件获取$listeners", this.$listeners);
},

Copy after login

输出结果：

可以发现输出了childData方法，这是我们在它的父组件自定义的监听事件。除次之外，$listeners可以通过v-on的形式再次传递给下层组件。

child1组件示例代码：

// src/views/child1.vue
<template>
  <div class="child-1">
    <p>child1组件</p>
    <div>
      <button @click="sendData">传递数据给父组件</button>
    </div>
    <div>
      <button @click="getParentData">使用$parent</button>
    </div>
    <div>
      <p>parent组件数据：{{ msg }}</p>
    </div>
    <!-- 子组件child1-child -->
    <child1-child v-bind="$attrs" v-on="$listeners"></child1-child>
  </div>
</template>

Copy after login

child1-child组件示例代码：

// src/views/child1-child.vue
mounted() {
  console.log("child1-child组件$attrs", this.$attrs);
  console.log("child1-child组件$listerners", this.$listeners);
},

Copy after login

输出结果：

可以看到在child1-child孙子组件中也获得了parent父组件中的childData自定义事件。使用 $listeners的好处在于：如果存在多层级组件，无需使用$ emit的方式逐级向上触发事件，只需要使用$listerners就可以得到父组件中的自定义事件，相当于偷懒了。

5.3 inheritAttrs

可能细心的小伙伴会发现，我们在使用$attrs时，child1子组件渲染的DOM节点上将我们传递的属性一起渲染了出来，如下图所示：

这并不是我们想要的，为了解决这个问题，我们可以在子组件中设置inheritAttrs属性。

官网解释：

默认情况下父作用域的不被认作 props 的 attribute 绑定 (attribute bindings) 将会“回退”且作为普通的 HTML attribute 应用在子组件的根元素上。当撰写包裹一个目标元素或另一个组件的组件时，这可能不会总是符合预期行为。通过设置 inheritAttrs 到 false，这些默认行为将会被去掉。而通过 (同样是 2.4 新增的) 实例 property $attrs 可以让这些 attribute 生效，且可以通过 v-bind 显性的绑定到非根元素上。

官网说了非常多，但是不太通俗，我们可以简单的理解。

通俗解释：

父组件传递了很多数据给子组件，子组件的props没有完全接收，那么父组件传递的这些数据就会渲染到HTML上，我们可以给子组件设置inheritAttrs 为false，避免这样渲染。

child1组件示例代码：

// src/views/child1.vue
props: {
  msg: {
    type: String,
    default: "",
  },
},
inheritAttrs: false,

Copy after login

输出结果：

此时我们节点上就没有那些无关的节点属性了。

5.4 总结

$attrs：用来传递属性，出了class、style之类的，它是一个对象。
$listeners：用来传递事件，出了原生事件，它也是一个对象。
$attrs和$ listeners这两个属性可以解决多层组件之间数据和事件传递的问题。
inheritAttrs解决未使用props接收的数据的属性渲染。

6.自定义事件：事件总线

在我们做项目的时候，会发现不相关的组件之间的数据传递是较为麻烦的，比如兄弟组件、跨级组件，在不使用Vuex情况下，我们可以使用自定义事件(也可以称作事件中心)的方式来实现数据传递。

事件中心的思想也比较简单：中间中心主要就两个作用：触发事件和监听事件。假如两个组件之间需要传递数据，组件A可以触发事件中心的事件，组件B监听事件中心的事件，从而让两个组件之间产生关联，实现数据传递。

实现步骤：

为了演示简单，我们在全局注册一个事件中心，修改main.js。

main.js代码如下：

// src/main.js
Vue.config.productionTip = false
Vue.prototype.$EventBus = new Vue()
new Vue({
  router,
  store,
  render: h => h(App)
}).$mount(&#39;#app&#39;)

Copy after login

child1组件示例代码：

<template>
  <div class="child-1">
    <p>child1组件</p>
    <div>
      <button @click="toChild2">向child2组件发送数据</button>
    </div>
  </div>
</template>
<script>
import Child1Child from "./child1-child";
export default {
  methods: {
    // 通过事件总线向child2组件发送数据
    toChild2() {
      this.$EventBus.$emit("sendMsg", "我是child1组件发来的数据");
    },
  },
};
</script>

Copy after login

child1组件中调用 $EventBus.$ emit向事件中心添加sendMsg事件，这个用法有点类似与props和$emit的关系。

child2组件2示例代码：

// src/views/child1.vue
<template>
  <div class="child-2">
    <p>child2组件</p>
    <div>
      <p>parent组件数据：{{ msg }}</p>
    </div>
  </div>
</template>
<script>
export default {
  props: {
    msg: {
      type: String,
      default: "",
    },
  },
  mounted() {
    this.$EventBus.$on("sendMsg", (msg) => {
      console.log("接收到child1发送来的数据", msg);
    });
  },
};
</script>

Copy after login

当我们点击child1组件中的按钮时，就会触发sendMsg事件，在child2组件中我们监听了该事件，所以会接收到child1组件发来的数据。

输出结果：

事件中心实现数据传递的这种方式，其实就是一个发布者和订阅者的模式，这种方式可以实现任何组件之间的通信。

7.provide和inject

这两个是在Vue2.2.0新增的API，provide和inject需要在一起使用。它们也可以实现组件之间的数据通信，但是需要确保组件之间是父子关系。

官网的解释：

这对选项需要一起使用，以允许一个祖先组件向其所有子孙后代注入一个依赖，不论组件层次有多深，并在其上下游关系成立的时间里始终生效。

官网的解释就已经说得很明确了，所以这里我们就不需要通俗的解释了，简单一句话：父组件可以向子组件（无论层级）注入依赖，每个子组件都可以获得这个依赖，无论层级。

parent示例代码：

// src/views/parent.vue
<script>
import child1 from "./child1.vue";
import child2 from "./child2.vue";
export default {
  provide() {
    return { parentData: this.msg };
  },
  data() {
    return {
      msg: "我是父组件的数据",
      msg1: "parent数据1",
      msg2: "parent数据2",
      msg3: "parent数据3",
      msg4: "parent数据4",
      childData: "",
    };
  },
  components: {
    child1,
    child2,
  },
};
</script>

Copy after login

child1-child组件示例代码：

// src/views/child1-child.vue
<template>
  <div class="child1-child">
    <p>我是孙子组件child1-child</p>
    <p>parent组件数据：{{parentData}}</p>
  </div>
</template>
<script>
export default {
  inject: ["parentData"],
  props: {
    msg1: {
      type: String,
      default: "",
    },
  },
  mounted() {
    console.log("child1-child组件$attrs", this.$attrs);
    console.log("child1-child组件$listerners", this.$listeners);
    console.log("child1-child组件获取parent组件数据", this.parentData)
  },
};
</script>

Copy after login

输出结果：

通过provide和inject结合的方式，我们在child1-child组件中获取到了parent组件中的数据。如果你下来尝试过的话，可能会发现一个问题，此时数据不是响应式，也就是parent组件更改了数据，child1-child组件中的数据不会更新。

想要变为响应式的，我们需要修改一下provide传递的方式。

parent代码如下：

// src/views/parent.vue
<script>
import child1 from "./child1.vue";
import child2 from "./child2.vue";
export default {
  provide() {
    return { parentData: this.getMsg };
  },
  data() {
    return {
      msg: "我是父组件的数据",
      msg1: "parent数据1",
      msg2: "parent数据2",
      msg3: "parent数据3",
      msg4: "parent数据4",
      childData: "",
    };
  },
  components: {
    child1,
    child2,
  },
  methods: {
    // 返回data数据
    getMsg() {
      return this.msg;
    },
  },
};
</script>

Copy after login

这个时候我们会发现数据变为响应式的了。

porvide和inject的原理可以参考下图：

8.Vuex和localStorage

这两种方式应该是小伙伴们在实际项目中使用最多的了，所以这里就不但展开细说，只是提一下这两者的区别即可。

Vuex：

Vuex是状态管理器，它存储的数据不是持久化存储，一旦刷新页面或者关闭项目数据便不见了。
Vuex存储的数据是响应式的。

localstorage：

loacalStorage是HTML5中的一种数据存储方式，持久化存储，存储的数据不是响应式的。

9.v-model

v-model是vue中的一个内置指令，它通常用在表单元素上以此来实现数据的双向绑定，它的本质是v-on和v-bind的语法糖。在这里我们也可以借助它来实现某些场景下的数据传递。注意，这儿的场景必须是父子组件。

parent组件示例代码：

<template>
  <div class="parent-box">
    <p>父级组件</p>
    <div>modelData： {{modelData}}</div>
    <child2 :msg="msg" v-model="modelData"></child2>
    <!-- 实际等同于 -->
    <!-- <child2 v-bind:value="modelData" v-on:input="modelData=$event"></child2>  -->
  </div>
</template>
<script>
import child2 from "./child2.vue";
export default {
  provide() {
    return { parentData: this.getMsg };
  },
  data() {
    return {
      modelData: "parent组件的model数据"
    };
  },
  components: {
    child1,
  },
};
</script>

Copy after login

child2组件示例代码：

<template>
  <div class="child-2">
    <p>child2组件</p>
    <div>
      <button @click="confirm">修改v-model数据</button>
    </div>
  </div>
</template>
<script>
export default {
  props: {
    value: {
      type: String,
      default: "",
    },
  },
  mounted() {
    console.log("child2组件接收附件见v-model传递的数据", this.value);
  },
  methods: {
    // 通过$emit触发父组件的input事件，并将第二个参数作为值传递给父组件
    confirm() {
      this.$emit("input", "修改parent传递的v-model数据");
    },
  },
};
</script>

Copy after login

我们在父组件中使用v-model向child2子组件传递数据，子组件的props中使用默认的value属性接收，在子组件中利用$emit触发父组件中默认input事件，此时传递的数据便会在子组件和父组件中发生变化，这就是数据双向绑定。

如果想要更加详细的学习v-model的使用，可以参考官网。

总结

Vue中组件通讯的方式有很多种，每一种应用的场景可能都有一些不一样，我们需要在合适的场景下选择合适的通讯方式。

Communication between parent and child components: props and $emit、$ $##r e f s and refs and$ Communication between generational components: provide and inject
No communication between relevant components: event bus, Vuex, localStorage
(Learning video sharing:
web front-end development

Introduction to Programming

)

The above is the detailed content of Summarize and share the various ways to implement communication between components in Vue, so you won't be afraid of interviews anymore!. For more information, please follow other related articles on the PHP Chinese website!