Combine two object into one

Question

In javascript I would like to combine two objects into one. I got

{
  test: false,
  test2: false
}

and

{
  test2: true
}

I tried to use $.extend, $.merge but all I get as an output is

{
  test2: true
}

How to get output like this

{
  test: false,
  test2: true
}

EDIT: Actually I have nested objects. What I need is to combine a and b as follows:

var a = { test: false, test2: { test3: false, test4: false } };
var b = { test2: { test4: true } };
// desired combined result:
{ test: false, test2: { test3: false, test4: true } }

but the actual result I get removes test3 from the nested test2 object.

Answer 1

var a = {
    test: false,
    test2: false
};

var b = {
    test2: true
};

var c = $.extend(a, b);

This will overwrite all properties on object a with a result of:

{
    test: false,
    test2: true
}

If you want a new, fresh object call .extend like so:

var c = $.extend({}, a, b);

This will do the same job, but it leaves object a untouched and creates a new object. See http://api.jquery.com/jQuery.extend/

---

update

In your comment you updated the object structures. Well, what you need there is a such called "deep clone". This is just one more parameter for the $.extend() call, like so:

var c = $.extend(true, a, b); // a gets overwritten
var c = $.extend(true, {}, a, b); // new object is created