How to Add an Object Literal to Another Object Literal in JavaScript

Question

I have an object literal, a:

a = {foo: 'foo'};

And I want to get b, the combination of a and {bar: 'bar'}:

b = {foo: 'foo', bar: 'bar'};

How can I do with without writing out all of the properties of a? i.e:

b = a + {bar: 'bar'};

And no, I do not want to have a be a property itself of b, as shown here:

b = {a: a, bar: 'bar'};

thefourtheye · Accepted Answer · 2013-12-22T02:30:12.363

1

You can iterate through the properties of a and add them to b, like this

for (var key in a) {
    b[key] = a[key];
}

If you want to add only the properties specific to a (properties which are not inherited), you can do it like this

for (var key in a) {
    if (a.hasOwnProperty(key) {
        b[key] = a[key];
    }
}

As S McCrohan points out, if you are using jQuery, you can use jQuery.extend method to do the same.

edited Dec 22 '13 at 02:30

answered Dec 22 '13 at 02:23

thefourtheye

If you're already using jQuery, you can make use of `jQuery.extend()`, though I wouldn't add jQuery to a project just for the sake of that. – S McCrohan Dec 22 '13 at 02:26
@SMcCrohan The OP didnt mention `jQuery` :) – thefourtheye Dec 22 '13 at 02:27
Agreed - tossing it out in case they're using it and didn't realize it could be helpful, but doing it in a comment because yours is the right vanilla JS answer. – S McCrohan Dec 22 '13 at 02:28
@SMcCrohan Added that in the answer :) Thanks :) – thefourtheye Dec 22 '13 at 02:30

1 Answers1