CODEWITHSUNDEEP
javascriptreference
Callum Rogers
Callum Rogers

Reputation: 15819

Will this copy the object or add a reference to it?

Let's say I have the following object:

var lol = {
    section: {},
    other: {foo: 'bar', foob: 'baz'}
};

Now if I do the following:

lol.section.other = lol.other;

will a reference be made linking section.other to other or will the entire other object be copied and placed in section?

Upvotes: 0

Views: 168

Answers (3)

jfriend00
jfriend00

Reputation: 707218

As SLaks said, javascript assigns objects as a reference (without copying). It's easy to test or see yourself:

var lol = {
    section: {},
    other: {foo: 'bar', foob: 'baz'}
};

lol.section.other = lol.other;

lol.other.foo = 'test';
console.log(lol.section.other.foo);   // will be 'test', not 'bar'

You can see it here: http://jsfiddle.net/jfriend00/r73LH/.

Upvotes: 1

RHT
RHT

Reputation: 5054

Like quite a few other OO languages, JavaScript also passes and assigns the object by reference therefore, you are only creating a new reference to an existing object.

Where JavaScript breaks away from other OO languages is in inheritance and in encapsulation. So be cautious in those areas.

Upvotes: 2

SLaks
SLaks

Reputation: 887305

You're creating two references to the same object.

Javascript objects are never implicitly copied.

Upvotes: 8

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