JavaScript 获取对象属性 API 详解：枚举性与 Symbol 处理

let obj = {
    name: 'Tom',
    age: 20
}
console.log(Object.getOwnPropertyDescriptor(obj,'name'))
// {
//    configurable: true
//    enumerable: true
//    value: "Tom"
//    writable: true
// }

var obj = {"name":"tom","sex":"male"};
Object.defineProperty(obj, "age", {value:"18", enumerable:false});
//增加不可枚举的属性age
Object.prototype.protoPer1 = function(){console.log("name is tom");};
//通过原型链增加属性，为一个函数
Object.prototype.protoPer2 = 2;
//通过原型链增加属性，为一个整型值2
for(var a in obj){
    console.log(a);
}
// name
//sex
//protoPer1
//protoPer2

var obj = {"name":"tom","sex":"male"};
Object.defineProperty(obj, "age", {value:"18", enumerable:false});
//增加不可枚举的属性age
Object.prototype.protoPer1 = function(){console.log("name is tom");};
//通过原型链增加属性，为一个函数
Object.prototype.protoPer2 = 2;
//通过原型链增加属性，为一个整型值2
console.log(Object.keys(obj));
//["name", "sex"]

var obj = {"name":"tom","sex":"male"};
Object.defineProperty(obj, "age", {value:"18", enumerable:false});
//增加不可枚举的属性age
Object.prototype.protoPer1 = function(){console.log("name is tom");};
//通过原型链增加属性，为一个函数
Object.prototype.protoPer2 = 2;
//通过原型链增加属性，为一个整型值2
console.log(Object.getOwnPropertyNames(obj));
//["name", "sex","age"]

var obj = {};
var a = Symbol('a');
var b = Symbol('b');
obj[a] = 'ikun';
obj[b] = 'cai';
var objectSymbols = Object.getOwnPropertySymbols(obj);
console.log(objectSymbols)
//[ Symbol(a), Symbol(b) ]

let obj = {
  [Symbol('my_key')]:1,
  enum:2,
  nonEnum:3
};
let objectKeys =Reflect.ownKeys(obj)
console.log(objectKeys)
//[ 'enum', 'nonEnum', Symbol(my_key) ]