慕标琳琳
你打印出来的是某个非原生类的实例就有名字:function A(){}var a = new A();console.log(a); // => A {}var b = {};console.log(b) // => {}, 比如Object类的实例不会显示Object//第三点是设置对象属性的可枚举/可读可写:var c = {c1: 'xxx'};Object.defineProperty(c, "c2", { enumerable: false, configurable: false, writable: false, value: "c2"});console.log(c); //c1就是显示的,c2是隐式的c.c1 = "666";c.c2 = '666';console.log(c); // =>{c1: "666", c2: "c2"},c1能写,c2的值不能 for(var cItem in c){ console.log(cItem + ': ' + c[cItem]);} // => 'c1: 666',c1能被枚举,c2不能。