Is JavaScript Pass by Reference?

[AleksandrHovhannisyan]

No description provided.

[aidane1]

Very high quality blog. Thank you for the information.

[omonkulov]

Amazing! Thank you!

[jaehyi]

This is THE best, in-depth explanation I have read on passing by reference and by value--thank you so much!

[Hail91]

Amazing explanation of a pretty tough concept for most. Well done, this is 100% going in my bookmark list to refer back to!

[JackYo]

I can not understand the ambiguous term "pass-by-reference" until I read this blog! Thank you!

[repiso-piyush]

cleared my misconception

[Goteii]

Great article, I could've lost my mind and got that wrong but..
"We’ve learned what references really are: aliases. And as it turns out, this is precisely the kind of reference that we’re talking about when we say a language has “pass by reference.” It’s all about aliasing arguments that were passed in!...." wouldn't that mean that IF javascript would be "pass-by-reference" and we would pass obj as an argument to a function which simply mutates that object's property "name" then we would mutate original object since the argument was just an alias of that object(simillar case to example of "swap" method in C++). Sorry for silly question but the last image in this article confused me

[AleksandrHovhannisyan]

@Goteii Not a silly question!

IF javascript would be "pass-by-reference" and we would pass obj as an argument to a function which simply mutates that object's property "name" then we would mutate original object since the argument was just an alias of that object(simillar case to example of "swap" method in C++)

No, the scenario you describe is how JavaScript currently works: If you pass an object to a function, you can access and mutate any of its properties, and the change will be reflected outside the function. If JavaScript did support passing by reference, we could change an object reference to point to an entirely new object inside a function, and that change would be reflected outside the scope of the function:

const swap = (objectA, objectB) => {
  const tempObject = objectA;
  objectA = objectB;
  objectB = tempObject;
}

const a = { value: 24 };
const b = { value: 42 };
swap(a, b);

If JavaScript supported pass by reference, a would now be { value: 42 } and b would be { value: 24 }. But this is not possible in JavaScript.