Vue 组件之间如何通讯

比如做一个 TodoList，有一个父组件 Index.vue

<template>
    <div>
        <Input @add="addHandler"/>
        <List :list="list" @delete="deleteHandler"/>
    </div>
</template>
<script>
import Input from './Input'
import List from './List'
export default {
    components: {
        Input,
        List
    },
    data() {
        return {
            list: [
                {
                    id: 'id-1',
                    title: '标题1'
                },
                {
                    id: 'id-2',
                    title: '标题2'
                }
            ]
        }
    },
    methods: {
        addHandler(title) {
            this.list.push({
                id: `id-${Date.now()}`,
                title
            })
        },
        deleteHandler(id) {
            this.list = this.list.filter(item => item.id !== id)
        }
    },
    created() {
        // eslint-disable-next-line
        console.log('index created')
    },
    mounted() {
        // eslint-disable-next-line
        console.log('index mounted')
    },
    beforeUpdate() {
        // eslint-disable-next-line
        console.log('index before update')
    },
    updated() {
        // eslint-disable-next-line
        console.log('index updated')
    },
}
</script>

子组件 List.vue

<template>
    <div>
        <ul>
            <li v-for="item in list" :key="item.id">
                {{item.title}}
                <button @click="deleteItem(item.id)">删除</button>
            </li>
        </ul>
    </div>
</template>
<script>
import event from './event'
export default {
    // props: ['list']
    props: {
        // prop 类型和默认值
        list: {
            type: Array,
            default() {
                return []
            }
        }
    },
    data() {
        return {
        }
    },
    methods: {
        deleteItem(id) {
            this.$emit('delete', id)
        },
        addTitleHandler(title) {
            // eslint-disable-next-line
            console.log('on add title', title)
        }
    },
    created() {
        // eslint-disable-next-line
        console.log('list created')
    },
    mounted() {
        // eslint-disable-next-line
        console.log('list mounted')
        // 绑定自定义事件
        event.$on('onAddTitle', this.addTitleHandler)
    },
    beforeUpdate() {
        // eslint-disable-next-line
        console.log('list before update')
    },
    updated() {
        // eslint-disable-next-line
        console.log('list updated')
    },
    beforeDestroy() {
        // 及时销毁，否则可能造成内存泄露
        event.$off('onAddTitle', this.addTitleHandler)
    }
}
</script>

另外一个子组件 Input.vue

<template>
    <div>
        <input type="text" v-model="title"/>
        <button @click="addTitle">add</button>
    </div>
</template>
<script>
import event from './event'
export default {
    data() {
        return {
            title: ''
        }
    },
    methods: {
        addTitle() {
            // 调用父组件的事件
            this.$emit('add', this.title)
            // 调用自定义事件
            event.$emit('onAddTitle', this.title)
            this.title = ''
        }
    }
}
</script>

以上，父子组件通讯是通过 props 和 $emit 来实现

兄弟间通讯则通过自定义事件 event.js，然后在子组件中分别引入 event.js

import Vue from 'vue'
export default new Vue()