Reference data type passing in function in Javascript

Question

I have a question about arguments passing in Javascript, as I know that, for primitive data types, when passing through a function, they got copied by value.

Haw about the reference data types?

As an example, see this code:

var person3 = new Object();
setName(person3);
console.log(person3)
function setName(obj){
  obj.Name = "remon"
}

For whom said that it is duplicate, it is not because I am asking the question from memory perspective and I am new in learning programming and the answers to that questions is so advanced for me.

Not much to qualify as an answer, so I'll just comment. Your instinct is right. referenced values get passed by reference, primitives get passed by value. — zfrisch, Jan 08 '19 at 19:16
Possibly a duplicate of https://stackoverflow.com/questions/518000/is-javascript-a-pass-by-reference-or-pass-by-value-language — antonku, Jan 08 '19 at 19:17
Possible duplicate of [Javascript confusion over variables defined by reference vs value](https://stackoverflow.com/questions/9473601/javascript-confusion-over-variables-defined-by-reference-vs-value) — zfrisch, Jan 08 '19 at 19:18
reference get passed as reference, so person3.Name will be "remon" — Vishnu, Jan 08 '19 at 19:18
for whom said that it is duplicate it is not because I am asking the question from memory perspective and i am new in learning programming and the answers to that questions is so advanced for me — , Jan 08 '19 at 19:20
@MinaShaker What do you mean by "memory perspective", and what language in the referenced answers do you not understand? — Bergi, Jan 08 '19 at 19:26
I mean where it is got stored is it on the heap or in the stack when passing a object to a function — , Jan 08 '19 at 19:28
Docs on data types https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures — Valery Baranov, Jan 08 '19 at 19:37
@ValeryBaranov thanks of course for your answer but what I want to say is that I know the data types and the difference between them but what I want to know when passing a variable from out side a function and it’s data type is object through a function do it got copied by reference or value — , Jan 08 '19 at 20:08

score 0 · Accepted Answer · answered Jan 08 '19 at 20:14

@MinaShaker well, your experiment shows, that it is copied by reference. We see {Name: 'remon'} in console.

var person3 = new Object();
setName(person3);
console.log(person3)
function setName(obj){
  obj.Name = "remon"
}

And here, if we 'copy' object before sending it to the function we will get {Name: 'simon'}

var person3 = { Name: "simon" };
setName(Object.assign({}, person3));
console.log(person3)
function setName(obj){
  obj.Name = "remon"
}

Reference data type passing in function in Javascript

1 Answers1