Vue 组件间传值

前言

Vue 作为现在比较火的框架之一，相信您在使用的过程中，也会遇到组件间传值的情况，本文将讲解几种 Vue 组件间传值的几种方法，跟着小编一起来学习一下吧！

实现

注意： 学习本文，需要您对 Vue 有一定的了解。

为了便于讲解，以下方法均假设父组件是 FatherComponent，子组件是 ChildComponent，兄弟组件是：BrotherComponent。我们来假定一种场景：点击父组件“传递给子组件”按钮，向子组件传递一条消息“I am your father.”；点击子组件“传递给父组件”按钮，向父组件传递一条消息“I am your child.”；点击子组件“传递给兄弟组件”按钮，向兄弟组件传递一条消息“I am your brother.”

1. 方法一

关键词： props、$emit

父组件 FatherComponent 代码：

<template>
  <div>
    <div>{{toFatherInfo}}</div>
    <ChildComponent :toChildInfo="toChildInfo" @toFather="toFather" @toBrother="toBrother"/>
    <BrotherComponent :toBrotherInfo="toBrotherInfo"/>
    <button @click="toChild">传递给子组件</button>
  </div>
</template>

<script>
  import ChildComponent from 'components/test/child-component'
  import BrotherComponent from 'components/test/brother-component'

  export default {
    components: {
      ChildComponent,
      BrotherComponent
    },
    data () {
      return {
        toFatherInfo: '',
        toChildInfo: '',
        toBrotherInfo: ''
      }
    },
    methods: {
      toFather (res) {
        this.toFatherInfo = res
      },
      toBrother (res) {
        this.toBrotherInfo = res
      },
      toChild () {
        this.toChildInfo = 'I am your father.'
      }
    }
  }
</script>

<style lang="less">
  button {
    font-size: 36px;
    border: none;
    padding: 20px;
    background-color: #999;
    color: #fff;
    width: 100%;
    margin-top: 30px;
  }
</style>

子组件 ChildComponent 代码：

<template>
  <div>
    <div>{{toChildInfo}}</div>
    <button @click="toFather">传递给父组件</button>
    <button @click="toBrother">传递给兄弟组件</button>
  </div>
</template>

<script>
  export default {
    props: {
      toChildInfo: {
        type: String
      }
    },
    methods: {
      toFather () {
        this.$emit('toFather', 'I am your child.')
      },
      toBrother () {
        this.$emit('toBrother', 'I am your brother.')
      }
    }
  }
</script>

<style lang="less">
</style>

兄弟组件 BrotherComponent 代码：

<template>
  <div>{{toBrotherInfo}}</div>
</template>

<script>
  export default {
    props: {
      toBrotherInfo: {
        type: String
      }
    }
  }
</script>

<style lang="less">
</style>

通过上面代码，不难发现，我们通过使用 props 来实现父组件给子组件传值；子组件向父组件传值时，借助 $emit 来实现；而子组件向兄弟组件传值时，将两者结合起来使用。

2. 方法二

关键词：独立的事件中心 eventHub

首先需要先创建 eventHub.js 文件，代码如下：

// 将在各处使用该事件中心
// 组件通过它来通信
import Vue from 'vue'
export default new Vue()

然后在组件中，可以使用 $emit, $on, $off 分别来分发、监听、取消监听事件。

父组件 FatherComponent 代码：

<template>
  <div>
    <div>{{info}}</div>
    <ChildComponent />
    <BrotherComponent />
    <button @click="toChild">传递给子组件</button>
  </div>
</template>

<script>
  import eventHub from '../../components/test/eventHub'
  import ChildComponent from 'components/test/child-component'
  import BrotherComponent from 'components/test/brother-component'

  export default {
    components: {
      ChildComponent,
      BrotherComponent
    },
    data () {
      return {
        info: ''
      }
    },
    created: function () {
      eventHub.$on('toFather', this.toFather)
    },
    // 最好在组件销毁前
    // 清除事件监听
    beforeDestroy: function () {
      eventHub.$off('toFather', this.toFather)
    },
    methods: {
      toFather (res) {
        this.info = res
      },
      toChild () {
        eventHub.$emit('toChild', 'I am your father.')
      }
    }
  }
</script>

<style lang="less">
  button {
    font-size: 36px;
    border: none;
    padding: 20px;
    background-color: #999;
    color: #fff;
    width: 100%;
    margin-top: 30px;
  }
</style>

子组件 ChildComponent 代码：

<template>
  <div>
    <div>{{info}}</div>
    <button @click="toFather">传递给父组件</button>
    <button @click="toBrother">传递给兄弟组件</button>
  </div>
</template>

<script>
  import eventHub from './eventHub'
  export default {
    data () {
      return {
        info: ''
      }
    },
    created: function () {
      eventHub.$on('toChild', this.toChild)
    },
    // 最好在组件销毁前
    // 清除事件监听
    beforeDestroy: function () {
      eventHub.$off('toChild', this.toChild)
    },
    methods: {
      toChild (res) {
        this.info = res
      },
      toFather () {
        eventHub.$emit('toFather', 'I am your child.')
      },
      toBrother () {
        eventHub.$emit('toBrother', 'I am your brother.')
      }
    }
  }
</script>

<style lang="less">
</style>

兄弟组件 BrotherComponent 代码：

<template>
  <div>{{info}}</div>
</template>

<script>
  import eventHub from './eventHub'
  export default {
    data () {
      return {
        info: ''
      }
    },
    created: function () {
      eventHub.$on('toBrother', this.toBrother)
    },
    // 最好在组件销毁前
    // 清除事件监听
    beforeDestroy: function () {
      eventHub.$off('toBrother', this.toBrother)
    },
    methods: {
      toBrother (res) {
        this.info = res
      }
    }
  }
</script>

<style lang="less">
</style>

3. 方法三

关键词：Vuex

我们需要创建 store.js 来存放数据：

import Vue from 'vue'
import Vuex from 'vuex'
Vue.use(Vuex)

export default new Vuex.Store({
  state: {
    fromFatherInfo: '',
    fromChildInfo: '',
    fromBrotherInfo: ''
  },
  mutations: {
    changeFromFatherInfo (state, fromFatherInfo) {
      state.fromFatherInfo = fromFatherInfo
    },
    changeFromChildInfo (state, fromChildInfo) {
      state.fromChildInfo = fromChildInfo
    },
    changeFromBrotherInfo (state, fromBrotherInfo) {
      state.fromBrotherInfo = fromBrotherInfo
    }
  }
})

实例化：

import Vue from 'vue'
import App from './App'
import store from './store'

new Vue({
  el: '#app',
  store,
  template: '<App/>',
  components: { App }
})

父组件 FatherComponent 代码：

<template>
  <div>
    <div>{{fromChildInfo}}</div>
    <ChildComponent />
    <BrotherComponent />
    <button @click="toChild">传递给子组件</button>
  </div>
</template>

<script>
  import ChildComponent from 'components/test/child-component'
  import BrotherComponent from 'components/test/brother-component'

  export default {
    components: {
      ChildComponent,
      BrotherComponent
    },
    computed: {
      fromChildInfo () {
        return this.$store.state.fromChildInfo
      }
    },
    methods: {
      toChild () {
        this.$store.commit('changeFromFatherInfo', 'I am your father.')
      }
    }
  }
</script>

<style lang="less">
  button {
    font-size: 36px;
    border: none;
    padding: 20px;
    background-color: #999;
    color: #fff;
    width: 100%;
    margin-top: 30px;
  }
</style>

子组件 ChildComponent 代码：

<template>
  <div>
    <div>{{fromFatherInfo}}</div>
    <button @click="toFather">传递给父组件</button>
    <button @click="toBrother">传递给兄弟组件</button>
  </div>
</template>

<script>
  export default {
    computed: {
      fromFatherInfo () {
        return this.$store.state.fromFatherInfo
      }
    },
    methods: {
      toFather () {
        this.$store.commit('changeFromChildInfo', 'I am your child.')
      },
      toBrother () {
        this.$store.commit('changeFromBrotherInfo', 'I am your brother.')
      }
    }
  }
</script>

<style lang="less">
</style>

兄弟组件 BrotherComponent 代码：

<template>
  <div>{{fromBrotherInfo}}</div>
</template>

<script>
  export default {
    computed: {
      fromBrotherInfo () {
        return this.$store.state.fromBrotherInfo
      }
    }
  }
</script>

<style lang="less">
</style>