SOURCE

const app = new Vue({
            el: "#app",
            data: {
                inp: "",
                todoList: [],
                checkList: []
            },
            methods: {
                add() {
                    if (!this.inp) {
                        alert("请输入信息！")
                    } else {
                        this.todoList.push({
                            isdo: false,
                            info: this.inp
                        })
                    }

                },
                del(index) {
                    this.todoList.splice(index, 1)
                },
                trueCount() {
                    let count = [...this.todoList].filter(item => {
                        return item.isdo == true
                    }).length;
                    return count;
                },
                falseCount() {
                    let count = [...this.todoList].filter(item => {
                        return item.isdo == false
                    }).length;
                    return count;
                }
            },
            mounted() {
                if (localStorage.todoList) {
                    this.todoList = JSON.parse(localStorage.todoList);
                }
                this.todoList.forEach((item, index) => {
                    if (item.isdo) { this.checkList.push(index) }
                })
                this.$watch("checkList",function(){
                        this.todoList.forEach((item,index)=>{
                            let i = this.checkList.indexOf(index)
                            if(i!=-1){
                                item.isdo=true;
                                console.log(item.info);
                            }else{
                                item.isdo=false;
                            }
                        })
                        localStorage.setItem("todoList", JSON.stringify(this.todoList))
                    })
            },
            watch: {
                todoList() {
                    localStorage.setItem("todoList", JSON.stringify(this.todoList))
                },
               
            }
        })
    

<div id="app">
        <div class="head">
            <div class="content">
                <h2>TodoList</h2>
                <div class="right">
                    <input type="text" v-model="inp" @keyup.enter="add">
                    <button @click="add">添加</button>
                </div>
            </div>
        </div>
        <div class="item_box">
            <div class="item">
                <div class="title">
                    <h2>正在进行</h2>
                    <span>{{falseCount()}}</span>
                </div>
                <ul>
                    <li v-for="(item,index) in todoList" :key="index" v-if="!item.isdo">
                        <input type="checkbox" :key="index" :value="index" v-model="checkList">
                        {{item.info}}
                        <button :id="index" @click="del(index)">删除</button>
                    </li>
                </ul>
            </div>
            <div class="item">
                <div class="title">
                    <h2>已经完成</h2>
                    <span>{{trueCount()}}</span>
                </div>
                <ul>
                    <li v-for="(item,index) in todoList" :key="index" v-if="item.isdo">
                        <input type="checkbox" :key="index" :value="index" v-model="checkList">
                        {{item.info}}
                        <button :id="index" @click="del(index)">删除</button>
                    </li>
                </ul>
            </div>
        </div>
    </div>

 * {
            margin: 0;
            padding: 0;
            list-style: none;
        }

        html,
        body {
            height: 100%;
        }

        #app {
            height: 100%;
            background-color: #ff6b6b;
            display: flex;
            flex-direction: column;
            align-items: center;
        }

        .head {
            padding: 20px 0;
            background-color: #ff9f43;
            width: 100%;
        }

        .content {
            margin: 0 auto;
            width: 50%;
            display: flex;
            justify-content: space-between;
            padding-right: 20px;
            box-sizing: border-box;
        }

        .content input {
            border-radius: 50px;
            font-size: 18px;
            outline: none;
            padding-left: 1%;
        }

        .content .right {
            display: flex;
            align-items: center;
        }

        .content .right button {
            flex-shrink: 0;
        }

        .item_box {
            width: 100%;
        }

        .item_box .item {
            margin: 0 auto;
            width: 50%;
        }

        .item_box .item .title {
            display: flex;
            align-items: center;
            justify-content: space-between;
        }

        .item_box .item .title span {
            display: inline-block;
            width: 25px;
            height: 25px;
            text-align: center;
            background-color: #feca57;
            border-radius: 50px;
            line-height: 25px;
        }

        .item_box .item ul li {
            border-left: 5px #01a3a4 solid;
            box-sizing: border-box;
            padding: 5px;
            background-color: #c8d6e5;
            border-radius: 5px;
            margin: 10px 0;
        }