1、对象的增删改查

 var obj = {
            name: 'jack',
            age: 12,
            weight: 45,
            hight: 160,
            say: function () {
                console.log('i from china');
            },
            work: function () {
                //不伦不类
                // obj.hight++
                // 对象里面，this 表示对象本身
                this.hight++
                console.log(obj.hight);//161
                console.log('i will go to park');
            },
            eat: function () {
                // obj.weight++
                this.weight++
                console.log(obj.weight);//46
                console.log('i eating dinner');
            }
        }
        // 删除对象的属性和方法
        delete obj.say
        delete obj.name
        obj.address = 'jx'
        obj.eat()//46
        obj.work()//161
        obj.work()//162
        console.log(obj);

2、带参数的对象方法

        function del() {
            var num = 3
            var arr = [1, 2, 3, 4, 5]
            for (var i = 0; i < arr.length; i++) {
                if (arr[i] === num) {
                    arr.splice(i, 1)
                }
            }
            return arr
        }

        console.log(del());//(4) [1, 2, 4, 5]

结果一样

function del(num) {
            // var num = 3
            var arr = [1, 2, 3, 4, 5]
            for (var i = 0; i < arr.length; i++) {
                if (arr[i] === num) {
                    arr.splice(i, 1)
                }
            }
            return arr
        }

        console.log(del(3));//(4) [1, 2, 4, 5]

 var school = {
            stu: [],
            total: 6,
            join: function (name) {
                this.stu.push(name)
                console.log(this.stu);
                // if (this.stu.length === this.total) {
                //     console.log('到齐');
                // } else {
                //     console.log('未到齐');
                // }
                this.stu.length === this.total ? console.log('到齐') : console.log('未到齐');
            },
            leave: function (name) {
                // for (var i = 0; i < this.stu.length; i++) {
                //     if (this.stu[i] === name) {
                //         this.stu.splice(i, 1)
                //     }
                // }
                // 效果一样
                var idx = this.stu.indexOf(name)
                if (idx !== -1) {
                    this.stu.splice(idx, 1)
                }

                console.log(this.stu);
                this.stu.length === this.total ? console.log('到齐') : console.log('未到齐');
                console.log(name + `早退了`);
            },
            bye: function () {
                this.stu = []
                console.log('已下课');
                console.log(this.stu);

            }

        }
        school.join('12')
        school.join('13')
        school.join('14')
        school.join('zhangsan')
        school.join('lisi')
        school.join('wangwu')  //(6) ["12", "13", "14", "zhangsan", "lisi", "wangwu"]
        school.leave('13')  //(5) ["12", "14", "zhangsan", "lisi", "wangwu"]
        school.bye()//[]