myHeader.vue

<template>
  <div class="todo-header">
    <input type="text" placeholder="请输入你的任务名称，按回车键确认" @keydown.enter="addHoby"/>
  </div>
</template>

<script>
//引入nanoid   方法：npm i nanoid
import {nanoid} from 'nanoid'
export default {
  name: "myHeader",
  props:["addTodo"],//不要忘记引号
  methods:{
    addHoby(e){
      //对输入内容进行判断，空的就不添加
      if(!e.target.value) return
      const inputData = e.target.value
      const itemObj = {id:nanoid(),title:inputData,todone:false}
      console.log(itemObj)
      //不要忘了写this
      this.addTodo(itemObj);
      //将输入框清空
      e.target.value = '';
    }
  }
};
</script>

<style scoped>
/*header*/
.todo-header input {
  width: 560px;
  height: 28px;
  font-size: 14px;
  border: 1px solid #ccc;
  border-radius: 4px;
  padding: 4px 7px;
}

.todo-header input:focus {
  outline: none;
  border-color: rgba(82, 168, 236, 0.8);
  box-shadow: inset 0 1px 1px rgba(0, 0, 0, 0.075),
    0 0 8px rgba(82, 168, 236, 0.6);
}
</style>

myList.vue

<template>
  <ul class="todo-main">
    <myItem v-for="item in todos" :key="item.id" :todosItem="item" :changeTodoDone='changeTodoDone' :deleTodos='deleTodos'></myItem> 
  </ul>
</template>

<script>
import myItem from "./myItem.vue";
export default {
  name: "myList",
  components: {myItem},
  props:['todos','changeTodoDone','deleTodos'],
};
</script>

<style scoped>
/*main*/
.todo-main {
  margin-left: 0px;
  border: 1px solid #ddd;
  border-radius: 2px;
  padding: 0px;
}

.todo-empty {
  height: 40px;
  line-height: 40px;
  border: 1px solid #ddd;
  border-radius: 2px;
  padding-left: 5px;
  margin-top: 10px;
}
</style>

myItem.vue

<template>
  <li>
    <label>
      <input type="checkbox"  :checked="todosItem.todone" @change="showId(todosItem.id)"/>
      <span v-text="todosItem.title"></span>
    </label>
    <button class="btn btn-danger" @click="dele(todosItem.id)">删除</button>
  </li>
</template>

<script>
export default {
  name: "myItem",
  props:["todosItem","changeTodoDone","deleTodos"],
  methods:{
    showId(id){
      console.log(id)
      //通知app组建中的todos中该id的todone改变true或false
      this.changeTodoDone(id)
    },
    dele(id){
      console.log(id)
      if(confirm('确定删除？')) this.deleTodos(id)
      //通知app组建中的todos中删除该id的数据
      
    }
  }
};
</script>

<style scoped>
/*item*/
li {
  list-style: none;
  height: 36px;
  line-height: 36px;
  padding: 0 5px;
  border-bottom: 1px solid #ddd;
}

li label {
  float: left;
  cursor: pointer;
}

li label li input {
  vertical-align: middle;
  margin-right: 6px;
  position: relative;
  top: -1px;
}

li button {
  float: right;
  display: none;
  margin-top: 3px;
}

li:before {
  content: initial;
}

li:last-child {
  border-bottom: none;
}
li:hover{
  background-color: darkgray;
}
/*鼠标悬浮时显示删除按键*/
li:hover button{
  display: block;
}
</style>

myFoot.vue

<template>
  <div class="todo-footer">
    <label>
      <!--checked为true勾中，false不勾
            第一种写法
      <input type="checkbox" :checked="isAll" @change="chengAll" />
           第二种写法  注意：v-model前没有：
      -->
      <input type="checkbox" v-model="isAll" />
    </label>
    <span>
      <span>已完成{{ doneNum }}</span> / 全部{{ todos.length }}
    </span>
    <!--该标签是button,不能用@change-->
    <button class="btn btn-danger" @click="clearn">清除已完成任务</button>
  </div>
</template>

<script>
export default {
  name: "myfoot",
  props: ["todos", "checkedAll","clearWork"],
  computed: {
    doneNum() {
      //pre当前值/上一次的值 currten为todos的item项
      return this.todos.reduce(
        (pre, currten) => pre + (currten.todone ? 1 : 0),
        0
      );
    },
    /*isAll() {
      // 判断选中的数量和todos的总量已否相等
      return this.doneNum === this.todos.length && this.todos.length > 0;
    },
    methods: {
      chengAll(e) {
        console.log(e.target.checked, 66);
        this.checkedAll(e.target.checked);
      },
    },*/
    isAll:{
      get(){
        return this.doneNum === this.todos.length && this.todos.length > 0
      },
      set(val){
        console.log(val)
        this.checkedAll(val);
      }
    }
  },
  methods:{
    clearn(){
      console.log(44)
      this.clearWork()
    }
  }
};
</script>

<style scoped>
/*footer*/
.todo-footer {
  height: 40px;
  line-height: 40px;
  padding-left: 6px;
  margin-top: 5px;
}

.todo-footer label {
  display: inline-block;
  margin-right: 20px;
  cursor: pointer;
}

.todo-footer label input {
  position: relative;
  top: -1px;
  vertical-align: middle;
  margin-right: 5px;
}

.todo-footer button {
  float: right;
  margin-top: 5px;
}
</style>

app.vue

<template>
  <div id="root">
    <div class="todo-container">
      <div class="todo-wrap">
        <myHeader :addTodo = 'addTodo'></myHeader>
        <myList :todos="todos" :changeTodoDone="changeTodoDone" :deleTodos="deleTodos"></myList>
        <myFoot :todos='todos' :checkedAll="checkedAll" :clearWork='clearWork'></myFoot>
      </div>
    </div>
  </div>
</template>

<script>
import myHeader from "./components/myHeader.vue";
import myList from "./components/myList.vue";
import myFoot from "./components/myFoot.vue";
export default {
  name: "App",
  components: {myHeader,myList,myFoot},
  methods:{
    //新增事项
    addTodo(value){
      this.todos.unshift(value)
    },
    //勾选or取消勾选
    changeTodoDone(value){
      this.todos.forEach((item)=>{
        if(item.id === value) item.todone = !item.todone 
      })
    },
    //删除数据
    deleTodos(id){
      this.todos =  this.todos.filter((item)=>{
        return item.id !== id
      })
    },
    //全选or全不选
    checkedAll(state){
      this.todos.forEach((item)=>{
        item.todone = state
      })
    },
    //删除已选任务
    clearWork(){
      console.log(555)
      this.todos = this.todos.filter((item)=>{
        return !item.todone 
      })
    }
  },
  data(){
    return{
      todos:[
      {id:'001',title:'喝酒',todone:false},
      {id:'002',title:'抽烟',todone:true},
      {id:'003',title:'烫头',todone:false}
      ]
    }
  }
};
</script>

<style>
/*base*/
body {
  background: #fff;
}

.btn {
  display: inline-block;
  padding: 4px 12px;
  margin-bottom: 0;
  font-size: 14px;
  line-height: 20px;
  text-align: center;
  vertical-align: middle;
  cursor: pointer;
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.2),
    0 1px 2px rgba(0, 0, 0, 0.05);
  border-radius: 4px;
}

.btn-danger {
  color: #fff;
  background-color: #da4f49;
  border: 1px solid #bd362f;
}

.btn-danger:hover {
  color: #fff;
  background-color: #bd362f;
}

.btn:focus {
  outline: none;
}

.todo-container {
  width: 600px;
  margin: 0 auto;
}
.todo-container .todo-wrap {
  padding: 10px;
  border: 1px solid #ddd;
  border-radius: 5px;
}
</style>