代码

代码路径

$ tree -N
.
├── App.vue
├── components
│   ├── MyFooter.vue
│   ├── MyHeader.vue
│   ├── MyItem.vue
│   └── MyList.vue
└── main.js

App.vue

<template>
  <div id="app">
    <div class="todo-container">
      <div class="todo-wrap">
        <!-- header -->
        <MyHeader @addTodo="addTodo"></MyHeader>
        <MyList :todos="todos"></MyList>
        <MyFooter
          :todos="todos"
          @checkAllTodo="checkAllTodo"
          @clearAllTodo="clearAllTodo"
        >
        </MyFooter>
      </div>
    </div>
  </div>
</template>

<script>
import MyFooter from "./components/MyFooter.vue";
import MyHeader from "./components/MyHeader.vue";
import MyList from "./components/MyList.vue";

import pubsub from "pubsub-js";
export default {
  name: "App",
  components: { MyFooter, MyHeader, MyList },
  data() {
    return {
      todos: [
        { id: "001", title: "抽烟", done: true },
        { id: "002", title: "喝酒", done: false },
        { id: "003", title: "开车", done: true },
      ],
    };
  },
  methods: {
    // 添加一个todo
    addTodo(todoObj) {
      // console.log('我是App，我接收到了数据：',x);
      this.todos.unshift(todoObj);
    },
    // 勾选or取消勾选一个todo
    checkTodo(id) {
      this.todos.forEach((todo) => {
        if (todo.id === id) {
          todo.done = !todo.done;
        }
      });
    },
    // 删除一个todo
    deleteTodo(_, id) {
      this.todos = this.todos.filter((todo) => {
        return todo.id !== id;
      });
    },
    // 全选or取消全选
    checkAllTodo(done) {
      this.todos.forEach((todo) => {
        todo.done = done;
      });
    },
    // 清除所有已完成的todo
    clearAllTodo() {
      this.todos = this.todos.filter((todo) => {
        return !todo.done;
      });
    },
    // 更新一个todo
    updateTodo(id, title) {
      this.todos.forEach((todo) => {
        if (todo.id === id) {
          todo.title = title;
        }
      });
    },
  },
  mounted() {
    this.$bus.$on("checkTodo", this.checkTodo);
    this.$bus.$on("updateTodo", this.updateTodo);
    // this.$bus.$on('deleteTodo',this.deleteTodo)
    this.pid = pubsub.subscribe("deleteTodo", this.deleteTodo);
  },
  beforeDestroy() {
    this.$bus.$off("checkTodo");
    this.$bus.$off("updateTodo");
    // this.$bus.$off('deleteTodo')
    pubsub.unsubcribe(this.pid);
  },
};
</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-edit {
  color: #fff;
  background-color: skyblue;
  border: 1px solid rgb(119, 181, 206);
  margin-right: 5px;
}

.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>

MyFooter.vue

<template>
  <div class="todo-footer" v-show="total">
    <label>
      <!-- <input type="checkbox" :checked="isAll" @change="checkAll"/> -->
      <input type="checkbox" v-model="isAll" />
    </label>
    <span>
      <span>已完成{{ doneTotal }}</span> / 全部{{ total }}
    </span>
    <button class="btn btn-danger" @click="clearAll">清除已完成任务</button>
  </div>
</template>

<script>
export default {
  name: "MyFooter",
  props: ["todos"],
  computed: {
    total() {
      return this.todos.length;
    },
    doneTotal() {
      // 第一种：使用遍历的方式
      // let i = 0
      // this.todos.forEach(todo => {
      //     if(todo.done){
      //         i++
      //     }
      // });
      // return i

      // 第二种：使用 reduce 处理
      // return this.todos.reduce((pre, todo) => pre+(todo.done ? 1 : 0), 0);

      // 第三种：使用filter处理
      const a = this.todos.filter((todo) => {
        return todo.done;
      });
      return a.length;
    },
    isAll: {
      get() {
        return this.total === this.doneTotal && this.total > 0;
      },
      set(value) {
        // this.checkAllTodo(value)
        this.$emit("checkAllTodo", value);
      },
    },
  },
  methods: {
    clearAll() {
      console.log("aaaa");

      // this.clearAllTodo()
      this.$emit("clearAllTodo");
    },
    //     checkAll(e){
    //         this.checkAllTodo(e.target.checked)
    //     }
  },
};
</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>

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"
      v-model="title"
      @keyup.enter="add"
    />
  </div>
</template>

<script>
import { nanoid } from "nanoid";
export default {
  name: "MyHeader",
  // props:['addTodo'],
  data() {
    return {
      title: "",
    };
  },
  methods: {
    add() {
      // 校验数据
      if (!this.title.trim()) {
        return alert("输入不能为空");
      }
      // 将用户的输入包装成一个todo对象
      const todoObj = { id: nanoid(), title: this.title, done: false };
      // 通知APP组件添加一个todo对象
      this.$emit("addTodo", todoObj);
      // 清空输入框
      this.title = "";
    },
  },
};
</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>

MyItem.vue

<template>
  <li>
    <label>
      <input
        type="checkbox"
        :checked="todo.done"
        @change="changeTodo(todo.id)"
      />
      <span v-show="!todo.isEdit">{{ todo.title }}</span>
      <input
        type="text"
        v-show="todo.isEdit"
        :value="todo.title"
        @blur="handleBlur(todo, $event)"
        ref="inputTitle"
      />
    </label>
    <button class="btn btn-danger" @click="handleDelete(todo.id)">删除</button>
    <button
      v-show="!todo.isEdit"
      class="btn btn-edit"
      @click="handleEdit(todo)"
    >
      编辑
    </button>
  </li>
</template>

<script>
import pubsub from "pubsub-js";
export default {
  name: "MyItem",
  // 声明接收todo对象
  props: ["todo"],
  methods: {
    // 勾选or取消勾选
    changeTodo(id) {
      // 通知App组件将对应的todo对象的done值取反
      // this.checkTodo(id)
      this.$bus.$emit("checkTodo", id);
    },
    // 删除todo--通过事件总线的方式
    // handleDelete(id){
    //     if(confirm('确定删除吗？')){
    //         this.$bus.$emit('deleteTodo',id)
    //     }
    // }
    // 删除todo--通过订阅发布
    handleDelete(id) {
      if (confirm("确定删除吗？")) {
        pubsub.publish("deleteTodo", id);
      }
    },
    handleEdit(todo) {
      if (todo.hasOwnProperty("isEdit")) {
        todo.isEdit = true;
      } else {
        this.$set(todo, "isEdit", true);
      }
      this.$nextTick(function () {
        this.$refs.inputTitle.focus();
      });
    },
    // 失去焦点回调 （真正执行修改逻辑）
    handleBlur(todo, e) {
      todo.isEdit = false;
      if (!e.target.value.trim()) return alert("内容不能为空");
      this.$bus.$emit("updateTodo", todo.id, e.target.value);
    },
  },
};
</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: gray;
}
li:hover button {
  display: block;
}
</style>

MyList.vue

<template>
  <ul class="todo-main">
    <MyItem v-for="t in todos" :key="t.id" :todo="t" />
  </ul>
</template>

<script>
import MyItem from "./MyItem.vue";

export default {
  name: "MyList",
  components: { MyItem },
  props: ["todos"],
};
</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>

main.js

import Vue from "vue";
import App from "./App.vue";

Vue.config.productionTip = false;

new Vue({
  el: "#app",
  components: { App },
  render: (h) => h(App),
  beforeCreate() {
    Vue.prototype.$bus = this;
  },
});

笔记

1. 语法：this.$nextTick(回调函数)
2. 作用：在下一次 DOM 更新结束后执行其指定的回调。
3. 什么时候用：当改变数据后，要基于更新后的新 DOM 进行某些操作时，要在 nextTick 所指定的回调函数中执行。