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).

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 );
    }
  }
};

Python的dict有'keys'方法，这真的很有用。我认为在JavaScript中我们可以有这样的东西:

function keys(){
    var k = [];
    for(var p in this) {
        if(this.hasOwnProperty(p))
            k.push(p);
    }
    return k;
}
Object.defineProperty(Object.prototype, "keys", { value : keys, enumerable:false });

编辑:但是@carlos-ruana的答案很好。我测试了Object.keys(窗口)，结果是我所期望的。

5年后再编辑:扩展Object不是一个好主意，因为它可能会与其他想要在其对象上使用键的库发生冲突，并且会在您的项目中导致不可预知的行为。@carlos-ruana答案是获取对象键的正确方法。

我仍然是JavaScript的初学者，但我写了一个小函数来递归地打印对象及其子对象的所有属性:

getDescription(object, tabs) {
  var str = "{\n";
  for (var x in object) {
      str += Array(tabs + 2).join("\t") + x + ": ";
      if (typeof object[x] === 'object' && object[x]) {
        str += this.getDescription(object[x], tabs + 1);
      } else {
        str += object[x];
      }
      str += "\n";
  }
  str += Array(tabs + 1).join("\t") + "}";
  return str;
}

简单JavaScript代码:

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

jQuery:

jQuery.each(obj, function(key, value) {
   // key is what you want.
   // The value is in: value
});