是否有一种jQuery方法只迭代对象自己的属性？

Question

I'm making a small jQuery-like library, and one thing striking me odd is the behavior of $.each .

In javascript we have a for...in loop:

for (var key in obj) {
    console.log(key + ': ' + obj[key]);
}

The problem with this, is that it will iterate over inherited properties as well, that is, properties coming from the object constructor's prototype.

One can know this using hasOwnProperty , for example. And jQuery could do that.

But, when you pass an object to $.each , it behaves exactly like a for...in , iterating over inherited properties as well. It also should be marginally slower, and requires a few more characters to type.

Check this fiddle to see it in action and look here for the source code of $.each .

So my question is, is there an object iteration method in jQuery that only includes own properties? If not, should a library behave like this?

Edit: Since jQuery does not do this, you can also answer if this is useful. I mean, I cannot see myself wanting to iterate over prototype properties, but maybe I'm missing something.

Answer 1

The jQuery behavior makes sense, as you can always choose to add the hasOwnProperty check in the loop - or not.

I can see that looping through inherited properties could be useful in some scenarios (cloning or sub-class or whatever you call it).