Invisible symbol after emoji is a variation selector.

Win+; pastes it into text after emoji. It is invisible character (selected on screenshot) which can be removed from source code after pasting emoji or stripped of by "⚙️".charAt(0).

In VSCode you can't select/delete this second char because caret treats this pair of chars as a whole, but in Notepad++ you can select this invisible char and delete it.

What does u'\ufe0f' in an emoji mean? Is it the same if I delete it?