简单:

for(var propertyName in myObject) {
   // propertyName is what you want
   // you can get the value like this: myObject[propertyName]
}

现在，您不会以这种方式获得私有变量，因为它们不可用。

编辑:@bitwiseplatypus是正确的，除非你使用hasOwnProperty()方法，否则你将获得继承的属性-然而，我不知道为什么任何熟悉面向对象编程的人会期望更少!一般来说，提出这个问题的人都听过道格拉斯·克罗克福德的警告，这让我有点困惑。同样，继承是OO语言的一个正常部分，因此也是JavaScript的一部分，尽管它是原型。

现在，也就是说，hasOwnProperty()对于过滤是有用的，但我们不需要发出警告，就好像获取继承属性是危险的一样。

EDIT 2: @bitwiseplatypus brings up the situation that would occur should someone add properties/methods to your objects at a point in time later than when you originally wrote your objects (via its prototype) - while it is true that this might cause unexpected behavior, I personally don't see that as my problem entirely. Just a matter of opinion. Besides, what if I design things in such a way that I use prototypes during the construction of my objects and yet have code that iterates over the properties of the object and I want all inherited properties? I wouldn't use hasOwnProperty(). Then, let's say, someone adds new properties later. Is that my fault if things behave badly at that point? I don't think so. I think this is why jQuery, as an example, has specified ways of extending how it works (via jQuery.extend and jQuery.fn.extend).

for (prop in obj) {
    alert(prop + ' = ' + obj[prop]);
}

在现代浏览器(ECMAScript 5)中，要获得所有可枚举属性，您可以做:

种(obj) (请检查链接以获得在旧浏览器上向后兼容的代码片段)

或者也可以得到不可枚举的属性:

Object.getOwnPropertyNames (obj)

查看ECMAScript 5兼容性表

额外的信息: 什么是可枚举属性?

我认为一个让我吃惊的案例是相关的:

var myObject = { name: "Cody", status: "Surprised" };
for (var propertyName in myObject) {
  document.writeln( propertyName + " : " + myObject[propertyName] );
}

但令我惊讶的是，输出是

name : Cody
status : Surprised
forEach : function (obj, callback) {
    for (prop in obj) {
        if (obj.hasOwnProperty(prop) && typeof obj[prop] !== "function") {
            callback(prop);
        }
    }
}

为什么?页面上的另一个脚本扩展了Object原型:

Object.prototype.forEach = function (obj, callback) {
  for ( prop in obj ) {
    if ( obj.hasOwnProperty( prop ) && typeof obj[prop] !== "function" ) {
      callback( prop );
    }
  }
};

下面是如何枚举一个对象的属性:

var params = { name: 'myname', age: 'myage' }

for (var key in params) {
  alert(key + "=" + params[key]);
}

如果你使用的是Underscore.js库，你可以使用函数键:

_.keys({one : 1, two : 2, three : 3});
=> ["one", "two", "three"]