如何迭代对象的原型属性 [英] How to iterate over an object's prototype's properties

问题描述

我有一些代码：

var obj = function() { }; // functional object
obj.foo = 'foo';
obj.prototype.bar = 'bar';

for (var prop in obj) {
    console.log(prop);
}

让我感到惊讶的是，记录的所有内容都是 FOO 。我期望for循环也迭代 obj 的原型的属性（即 bar ），因为我没有检查 hasOwnProperty 。我在这里错过了什么？是否有一种惯用的方法来迭代原型中的所有属性？

What surprised me is that all that is logged is foo. I expected the for loop to iterate over the properties of the obj's prototype as well (namely bar), because I did not check for hasOwnProperty. What am I missing here? And is there an idiomatic way to iterate over all the properties in the prototype as well?

我在Chrome和IE10中对此进行了测试。

I tested this in Chrome and IE10.

提前致谢。

推荐答案

您正在迭代构造函数的属性，您必须创建一个实例。该实例继承自构造函数的 prototype 属性：

You're iterating over the constructor's properties, you have to create an instance. The instance is what inherits from the constructor's prototype property:

var Ctor = function() { }; // constructor function
Ctor.prototype.bar = 'bar';
var obj = new Ctor(); // instantiation

// adds own property to instance
obj.foo = 'foo';

// logs foo and bar
for (var prop in obj) {
    console.log(prop); 
}

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