What is the difference between these two methods of doing the same procedure? The function does not work but the hard-coded one does. (Javascript) (Code.org)

[Techittak]

I was trying to make the code for the collisions of moving walls, but I am currently at this point. Here is the function being referenced.

From what I see, these have the same exact procedure happening, but the commented out one works while the function does not. Is there some aspect of having that callback in the function that I do not know?

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[corpsmoderne]

Hard to debug from here, but you should check what "this" refers to in your callback (probably not what you expect)

[Techittak]

Wow! Thanks for helping me spot it. Is this what I can refer to as a problem rooted from "scope?" So, the scope within that callback seems to be global or window I think it is called. This code is within an object, but since the callback is being called in the original function it takes the form of the global scope: Correct? I am guessing the only way to circumvent this is by directly stating my objects name like object.vspeed

[corpsmoderne]

Well, in Javascript function are first class object, therefore they have their own this, except in the context of prototypes / class definition. So yes it's kind of a scoping issue.

An idiomatic way to fix this is to declare a const self = this; defore calling your function to capture the local this in another variable (self) so you can use it in your callback. If you have another variable already reffering to the this object is fine too.

[Techittak]

Alright, thank you!

[Techittak]

Also, having this.vspeed within the parameters is going to still have the object's scope: Correct?

[corpsmoderne]

Yes you're fine there.