Vue中的$emit组件事件运用

<template>
  <div id="app">
     <!-- header -->
     <Header/>
     <AddTodo v-on:handleAdd="handleAdd"/>
    <Todos :todos="todos" @handleDelete="handleDelete"/>
    
    </div>
 
</template>

<script>
import Todos from "./components/Todos";
import Header from "./components/layout/Header";
import AddTodo from "./components/layout/AddTodo";
export default {
  
  name:"app",
  data(){
    return{
      msg:"hello",
      todos:[
        {
          id:1,
          title:"代办事项1",
          completed:false
        },
        {
          id:2,
          title:"代办事项2",
          completed:false
        },
        {
          id:3,
          title:"代办事项3",
          completed:false
        },
      ]
    }
  },
  components:{
    Todos,
    Header,
    AddTodo,
  },
  methods:{
    handleDelete(id){
      // console.log(id);
      this.todos=this.todos.filter(todo =>todo.id !==id)
    },
    handleAdd(newTodo){
      // this.todos.unshift(newTodo);
      this.todos=[...this.todos,newTodo]
    }
  }
}
</script>


<style>
*{
  box-sizing:border-box;
  margin: 0;
  padding: 0;
}

body{
  font-family: Arial, Helvetica, sans-serif;
  line-height: 1.4;
}
</style>

<template>
  <div>
    <div :key="todo.index" v-for="(todo) in todos">
      <!-- <Todoitem :todo="todo" @deleteItem="deleteItem"/> -->
      <Todoitem :todo="todo" @deleteItem="$emit('handleDelete',todo.id)"/>
    </div>
  </div>
</template>

<script>
import Todoitem from './Todoitem';
export default {
  name:"Todos",
  props:{
    todos:{
      type:Array
    }
  },
  components:{
    Todoitem
  },
  methods:{
    // deleteItem(id){
    //   console.log(id);
    // }
  }
};
</script>

<style scoped>

</style>

<template>
    <div class="todo-item" :class="{'is-complete':todo.completed}">
    <p>
      <input type="checkbox" @change="markComplete">
      {{todo.title}}
      <button class="del" @click="$emit('deleteItem',todo.id)">x</button>
    </p>
    </div>
</template>

<script>
export default {
    name:"Todos",
    props:["todo"],
    methods:{
      markComplete(){
        // console.log(this.todo);
        this.todo.completed = !this.todo.completed;
      }
    }

}
</script>

<style scoped>
.todo-item{
  background: #f4f4f4;
  padding: 10px;
  border-bottom: 1px #ccc dotted;

}
.is-complete{
  text-decoration: line-through;
}
.del{
  background: #ff0000;
  color: #fff;
  border: none;
  padding: 5px 9px;
  border-radius: 50%;
  cursor: pointer;
  float: right;
}

</style>

<template>
  <div>
    <form @submit="addTodo">
      <input v-model="title" type="text" name="title" placeholder="请添加代办事项……"/>
      <input type="submit" value="添加" class="btn">
    </form>
  </div>
</template>

<script>
import uuid from "uuid";
export default {
  name:"AddTodo",
  data(){
    return{
      title:""
    }
  },
  methods:{
    addTodo(e){
      e.preventDefault();
      // console.log('title:', this.title)
     const newTodo={
       id:uuid.v4(),
       title:this.title,
       completed:false
     };
     console.log('tag',newTodo )
     //注册事件
     this.$emit("handleAdd",newTodo)
     this.title="";
    }
  }
}
</script>
<style scoped>
form{
  display:flex;
}
input[type="text"]{
  flex:10;
  padding: 5px;
}
input[type="submint"]{
  flex: 2;
}
.btn{
  display: inline-block;
  border: none;
  background: #555;
  color:#fff;
  padding:7px 20px;
  cursor: pointer;
}
.btn:hover{
  background: #666;
}
</style>

<template>
  <header class="header">
      <h1>代办事项</h1>
  </header>
</template>

<script>
export default {
  name: 'Header',
 
}
</script>

<!-- Add "scoped" attribute to limit CSS to this component only -->
<style scoped>
.header{
    background: #333;
    color:#fff;
    text-align: center;
    padding:10;
}
</style>