CODEWITHSUNDEEP
javascriptobject
isaac tschampl
isaac tschampl

Reputation: 398

Are javascript object variables just reference type?

If you have a javascript variable that is an object and you make a new variable equal the the first variable, does it create a new instance of the object, or do they both reference the same object?

Upvotes: 2

Views: 218

Answers (4)

Kiknaio
Kiknaio

Reputation: 76

Both will refer to the same object. If you want to create a new instance:

    var Person = function() {
      this.eyes = 2,
      this.hands = 2
    };    

    var bob = new Person();
    var sam = new Person();

Those two are different objects.

Here is the answer: when you create an object and then assign it to another it will refer to the same object.

Here is an example: 

var hacker = {
  name : 'Mr',
  lastname : 'Robot'
};

console.log(hacker.name + '.' + hacker.lastname);
// Output Mr.Robot

// This variable is reference to hackers object
var anotherPerson = hacker;

console.log(anotherPerson.name + '.' + anotherPerson.lastname);
// Output Mr.Robot

// These will change hacker object name and lastname
anotherPerson.name = 'Elliot';
anotherPerson.lastname = 'Alderson';

console.log(anotherPerson.name + ' ' + anotherPerson.lastname);
// Output "Elliot Alderson"

// After it if you try to log object hacker name and lastname it would be:
console.log(hacker.name + '.' + hacker.lastname);
// Output "Elliot Alderson"

You can check the link here and play with it. It is not to complicated. JSBIN Object Hacker

Upvotes: 1

Nikhilesh Shivarathri
Nikhilesh Shivarathri

Reputation: 1670

Object Reference explained!

Look the image for better understanding. When you create an object, suppose s1 it is having just a reference in the memory heap and now when you create another object say s2 and say s1 = s2 that means both the objects are actually pointing to the same reference. Hence when you alter either of them, both change.

Object Reference Example

Upvotes: 1

redneb
redneb

Reputation: 23870

They always reference the same object. We can see that by trying the following:

var x = {foo:11};
var y = x;
y.foo = 42;
console.log(x.foo);
// will print 42, not 11

Upvotes: 3

Michał Młoźniak
Michał Młoźniak

Reputation: 5556

If you mean something like this

var a = { foo: "foo" };
var b = a;

then yes. They reference the same object.

Upvotes: 0

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