Why old objects are updated when updating assigned new object with old one

Asked Oct 05 '21 at 15:55

Active Oct 05 '21 at 16:04

Viewed 123 times

Kinda messy, but take a look at this and you will understand

var oldObject = { hello: "world" },
    newObject = { who: "cares" };

newObject["newStuff"] = oldObject;

console.log(oldObject)
console.log(newObject)

newObject["newStuff"]["hello"] = null;

console.log(oldObject)
console.log(newObject)

I am not having issues but i really want to know why !!!!

After comments i recieved this example: x.member = "bar"; // Updated original object
x = { member: "bar" }; // Didnt updated it

BUT let's say i have a really big big big object with 10 or 15 arguments, how can i use the second idea without putting a mess inside my code? :)

edited Oct 05 '21 at 16:04

asked Oct 05 '21 at 15:55

xPyth

3

because it is a reference, not a copy – epascarello Oct 05 '21 at 15:57
1

https://stackoverflow.com/questions/518000/is-javascript-a-pass-by-reference-or-pass-by-value-language might help? – evolutionxbox Oct 05 '21 at 15:58
Please do consider using https://justjavascript.com/ – evolutionxbox Oct 05 '21 at 16:00
1

@TusharShahi This is neither a deep copy nor a shallow copy. It's not a copy at all. – Barmar Oct 05 '21 at 16:01
FYI `newObject["newStuff"]` is more commonly written `newObject.newStuff` (unless the key includes whitespace). – jarmod Oct 05 '21 at 16:02
1

TLDR: https://stackoverflow.com/a/37290849/1046690 – AGE Oct 05 '21 at 16:02

Why old objects are updated when updating assigned new object with old one

0 Answers0