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
– zfrisch, Commented Jan 8, 2019 at 19:16
Possibly a duplicate of stackoverflow.com/questions/518000/… — antonku
– antonku, Commented Jan 8, 2019 at 19:17
Possible duplicate of Javascript confusion over variables defined by reference vs value — zfrisch
– zfrisch, Commented Jan 8, 2019 at 19:18
reference get passed as reference, so person3.Name will be "remon" — Vishnu
– Vishnu, Commented Jan 8, 2019 at 19:18
Docs on data types developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures — Valery Baranov
– Valery Baranov, Commented Jan 8, 2019 at 19:37

Valery Baranov · Accepted Answer · 2019-01-08 20:14:48Z

0

@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"
}

answered Jan 8, 2019 at 20:14

Valery Baranov

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