Why can't I set a variable by having it as an argument of a function?

Asked Jan 07 '22 at 17:37

Active Jan 07 '22 at 17:37

Viewed 35 times

I want my code to be DRY which is why I wrote a function which gets a variable as an argument, which I'm giving a value in that function.

Simplified code:

private bar: boolean | undefined;

private foo(variable: boolean): void {
  variable = true;
}

this.foo(this.bar);

The variable bar stays undefined and I don't get why. Seems like I don't understand something very fundamental. Anyone can help?

asked Jan 07 '22 at 17:37

dreamyleamy

1

A parameter introduces a variable, and javascript is pass-by-value for primitives (pass-by-copy-of-reference for objects) – ASDFGerte Jan 07 '22 at 17:39
Assigning to params doesn't affect the binding in other scopes, although mutating them works as you seem to expect. – Jared Smith Jan 07 '22 at 17:40
`variable` is local to the `foo` function. If you want to change `this.bar` then you'll have to reference it as such. – Đinh Carabus Jan 07 '22 at 17:40
thank you guys for the quick help! :) – dreamyleamy Jan 07 '22 at 17:48

0 Answers0