For Java, IntelliJ offers color/font/highlighting for local variables based on whether they are ever reassigned. (Settings->Editor->Colors & Fonts->Java, Variables->Local variable, Variables->Reassigned local variable). Please add equiva...
There are no such styles there for those languages (but they're there for Java in IntelliJ IDEA). I also see no tickets (implemented / declined or just any at all) about this "reassigned parameter" / "reassigned local variable" styles in WebStorm Issue Tracker. Feel free ...