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Object.getOwnPropertyNames()、for in、Object.keys() 三者区别 #10

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ceerqingting opened this issue Jul 3, 2018 · 0 comments

Owner

ceerqingting commented Jul 3, 2018

举个栗子：

  var obj = { a: 1 };
  Object.defineProperty(obj, 'b', { value: 2, enumerable: false });
  Object.prototype.c = 3;
  Object.prototype.d = function() { console.log(1) }

Object.getOwnPropertyNames() : 返回对象自有的所有属性，包括可枚举和不可枚举的

Object.getOwnPropertyNames(obj)
[a, b]

for in : 返回对象自有和继承原型的可枚举属性

for( var i in obj ) {
  console.log(i)
}
a
c
d

Object.keys() :返回对象自有可枚举属性

Object.keys(obj)
[a]

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