Vue

(function (window) {

    'use strict';

    const vm = new Vue ({

        el:'#app',

        data:{

            name:'',

            list:[

                {id:1,name:'抽烟',completed:false},

                {id:2,name:'喝酒',completed:true},

                {id:3,name:'烫头',completed:false},

            ]

        },

        methods:{

            add(){

                if(this.name.trim() === ''){

                    return

                }

                 let id

                 if(this.name.length === 0){

                    id = 1

                }else{

                    id=this.name[this.name.length - 1].id+1    

                }

//数据为0的时候 -1产生的错误

                

                this.list.push({id,name:this.name,completed:false})

                this.name=''

            

            }

        },

    })

})(window);