如何在自定义toJSON方法中使用JSON.stringify？

So, JSON.stringify provides a great way to turn a JS object like:

所以，JSON.stringify提供了一个转换JS对象的好方法：

var baz = {"foo":1, "bar":someFunction};

in to a JSON string like:

进入JSON字符串，如：

{"foo":1}

It does this with an optional second argument that controls which fields should be serialized:

它使用可选的第二个参数来控制应该序列化哪些字段：

JSON.stringify(baz, ["foo"]);

That's great, but there's a problem. Let's say your "baz" is actually the property of another object, and you want to serialize that other object:

那很好，但是有问题。假设您的“baz”实际上是另一个对象的属性，并且您想序列化该另一个对象：

someObject.baz = {"foo":1, "bar":someFunction};
JSON.stringify(someObject, ["baz"]);

Well, normally you would just define a toJSON method on baz, eg.:

好吧，通常你只需要在baz上定义一个toJSON方法，例如：

someObject.baz = {"foo":1, "bar":someFunction};
someObject.baz.toJSON = function() { /* logic to "toJSON" baz*/ }
JSON.stringify(someObject, ["baz"]);

Now, as I mentioned earlier, we have the perfect logic to "toJSON" baz already:

现在，正如我之前提到的，我们已经有了“toJSON”baz的完美逻辑：

someObject.baz.toJSON = function() {
    return JSON.stringify(baz, ["foo"]);
}

but if you try putting that in to your toJSON, you'll get a recursion error, because stringify will trigger the toJSON, which will trigger the stringify, which will ... :-(

但是如果你尝试将它放到你的toJSON中，你会得到一个递归错误，因为stringify会触发toJSON，这将触发stringify，这将... :-(

You can work around this with a hack:

你可以通过hack来解决这个问题：

someObject.baz.toJSON = function() {
    var oldToJON = this.toJSON;
    this.toJSON = null;
    var ret = JSON.stringify(baz, ["foo"]);
    this.toJSON = oldToJON;
    return ret;
}

But ... that just seems wrong. So, my question is: is there any way you can utilize the nifty built-in serialization power of JSON.stringify inside a toJSON method of an object (without having to hide the toJSON method itself during the stringify operation)?

但是......那似乎是错的。所以，我的问题是：有没有什么方法可以在对象的toJSON方法中利用JSON.stringify的漂亮的内置序列化功能（在stringify操作期间不必隐藏toJSON方法本身）？

1 个解决方案

#1

Crockford's json2.js says:

克罗克福德的json2.js说：

A toJSON method does not serialize: it returns the value represented by the name/value pair that should be serialized, or undefined if nothing should be serialized.

toJSON方法不会序列化：它返回应该序列化的名称/值对表示的值，如果没有任何序列化，则返回undefined。

So you are simply expected to return the value that you want serialized. In your case, baz.toJSON should simply return the portion of the baz object that you want serialized:

因此，您只需要返回要序列化的值。在您的情况下，baz.toJSON应该只返回您想要序列化的baz对象的部分：

someObject.baz.toJSON = function() {
  return { foo: this.foo };
};

#1