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JavaScript JavaScript Basics (Retired) Creating Reusable Code with Functions Variable Scope

Posted by Azul Bleu
Azul Bleu
Courses Plus Student 1,015 Points

Isn't there times when what you want exactly is to override the global scope?

In the video, he says that it's best to initialise a variable to make it "local" so to speak, in each function. Basically, that I should always declare variables inside functions using the keyword var. But there's times when we actually could /want/ to override an existing variable in the global scope, right? For example, photo galleries, where you could want to advance or go back by a number, depending on where you are.

I may have answered myself, but I still want to be 100% sure. Is this is a rule set in stone? Is there a reason I may want to actually do this everytime?

1 Answer

Steven Parker
Steven Parker
231,271 Points
Steven Parker
Steven Parker
231,271 Points

Yes, it's possible that a function might access global variables, and in that case there would be no declaration of that variable within the function.

But when possible, "best practice" would be to handle communication in or out of a function using arguments and return values. This makes it much easier to someone reading the code to understand what a function does while reading the code near where it is called.

jeremy krans
jeremy krans
6,178 Points

What if you are accessing an object or array in that function? If the array is specific to that function should you move it inside the function or is it ok to leave the array global?

Steven Parker
Steven Parker
231,271 Points
Steven Parker
Steven Parker
231,271 Points

Recommended "best practice" is to locate any variables, including arrays, that are used exclusively by a function so their scope is limited to that function.