es5 对象方法

<script>

        // 用户获取对象的自身所有的属性

        var obj = {

            id: 1,

            pname: 1999,

            num: 2000

        };

        var arr = Object.keys(obj);

        console.log(arr); //  ["id", "pname", "num"]

        arr.forEach(function(value) {

            console.log(value);

        })

 

 

 

<script>

        var obj = {

            id: 1,

            pname: '小米',

            num: 1999

        };

        // Object.defineProperty(obj, 'num', {

        //     value: 1000

        // });

        // console.log(obj); // {id: 1, pname: "小米", num: 1000}

        // Object.defineProperty(obj, 'price', {

        //     value: 9.9

        // });

        // console.log(obj); // {id: 1, pname: "小米", num: 1999, price: 9.9}

        // Object.defineProperty(obj, 'id', {

        //     // 是否允许修改这个属性

        //     writable: false

        // });

        // obj.id = 2;  // false 不允许修改

        // console.log(obj);

        Object.defineProperty(obj, 'address', {

            value: '山东蓝翔',

            // 是否允许修改这个属性

            writable: false,

            // 加上这个属性 就不会被遍历出来

            enumerable: false,

            // 不允许被删除

            configurable: false

        });

        console.log(obj);

        var arr2 = Object.keys(obj);

        console.log(arr2); //  ["id", "pname", "num"]

        delete obj.address;

        console.log(obj);

        delete obj.pname; // 没有规定就可以被删除

        console.log(obj); //{id: 1, num: 1999, address: "山东蓝翔"}

    </script>