Object.keys定义:返回一个对象可枚举属性的字符串数组; Object.getOwnPropertyNames定义:返回一个对象可枚举、不可枚举属性的名称; 属性的可枚举性、不可枚举性:定义:可枚举属性是指那些内部 “可枚举” 标志设置为 true 的属性,对于通过直接的赋值和属性初始化的属性,该标识值默认为即为 true,对于通过 Object.defineProperty 等定义的属性,该标识值默认为 false。
var obj = { "prop1": "v1" };
Object.defineProperty(obj, "prop2", { value: "v2", enumerable: false });
console.log(Object.keys(obj).length); //output:1
console.log(Object.getOwnPropertyNames(obj).length); //output:2
console.log(Object.keys(obj)); //output:Array[1] => [0: "prop1"]
console.log(Object.getOwnPropertyNames(obj)); //output:Array[2] => [0: "prop1", 1: "prop2"]
综合实例:
var obj = { "prop1": "v1" };
Object.defineProperty(obj, "prop2", { value: "v2", enumerable: false});
console.log(obj.hasOwnProperty("prop1")); //output: true
console.log(obj.hasOwnProperty("prop2")); //output: true
console.log(obj.propertyIsEnumerable("prop1")); //output: true
console.log(obj.propertyIsEnumerable("prop2")); //output: false
console.log('prop1' in obj); //output: true
console.log('prop2' in obj); //output: true
for (var item in obj) {
console.log(item);
}
//output:prop1
for (var item in Object.getOwnPropertyNames(obj)) {
console.log(Object.getOwnPropertyNames(obj)[item]);
}
//ouput:[prop1,prop2]