I’m doing the FCC lesson “Global Scope and Functions”. It uses a variable oopsGlobal in the function. But it doesn’t seem to me that the variable is declared anywhere, I only see it being defined. Do you need to declare a variable? Thanks // Declare your variable here var myGlobal = 10; function f…

@lasjorg Yes I think you mostly did answer it, thanks. I also didn’t realize that you could declare a variable without using var, let, or const (or maybe others one I don’t know about). My point is, I thought code like oopsGlobal = 5; or inGlobal = 'I really should not be here wasn’t just a “bad ide…

It is pretty much for historical reasons that it works without declaring. It was to make it more user-friendly so an inexperienced programmer that forgot to declare the variable would be “helped” by the language. It turns out to be a really bad idea and something that should never have been implemen…

Do variables need to be declared if they're being used in a function?

JavaScript

lasjorg October 20, 2019, 2:39pm 2

Not sure if I answered your question in the other thread.

I’d suggest giving this a good read.
You Don’t Know JS Yet: Scope & Closures - 2nd Edition

Topic		Replies	Views
Basic JavaScript - Global Scope and Functions JavaScript	6	532	May 30, 2023
Not always global? JavaScript	2	371	November 23, 2022
JavaScript: Global Scope and Functions Excercise JavaScript	2	725	February 2, 2021
I thought it was a global variable WITHOUT 'var'? JavaScript	8	3205	October 14, 2021
How can a user declare a variable within a function if established methods don't work?	10	2171	January 17, 2021

Do variables need to be declared if they're being used in a function?

Related topics