Object.getOwnPropertyNames 和 Object.keys()

var obj = {'a':'a','b':'b'};

Object.defineProperties(obj,{
    "c":{value:'c',enumerable:0},
    "d":{value:'d',enumerable:!0} 
})
// obj {a: "a", b: "b", d: "d", c: "c"}
Object.keys(obj)        // ["a", "b", "d"]
Object.getOwnPropertyNames(obj)       // ["a", "b", "c", "d"]

Object.getOwnPropertyNames   返回自身對象的所有屬性的數組集合

Object.keys()    返回自身對象可枚舉屬性的數組集合