对象扩展

 1. Object.is(v1, v2) : 判断2个数据是否完全相等
 2. Object.assign(target, source1, source2..) : 将源对象的属性复制到目标对象上
 3. __proto__属性 : 隐式原型属性
 4. 增强的对象写法
 

console.log('abc'==='abc');
console.log(Object.is('abc', 'abc'));
console.log(0===-0);
console.log(Object.is(0, -0));
console.log(NaN===NaN);
console.log(Object.is(NaN, NaN));

var target = {a: 1, b: 1};
var source1 = {b: 2, c: 2};
var source2 = {c: 3, d: 4};
Object.assign(target, source1, source2);
console.log(target);

var obj1 = {
    name : 'Tom',
    setName : function (name) {
        this.name = name;
    }
};

var obj2 = {};
obj2.__proto__ = obj1;
obj2.setName('Jack');
console.log(obj2.name);


function getPoint() {
    var x = 1;
    var y = 2;
    return {x, y};
    return {x:x,y:y };//(传统对象写法,key:value)
}
console.log(getPoint());