No it isn't! You know why? Because there is TypeScript. What is TypeScript? According to typescriptlang.org:
"TypeScript is a language for application-scale JavaScript development.
TypeScript is a typed superset of JavaScript that compiles to plain JavaScript.
Any browser. Any host. Any OS. Open Source."
I use it for almost every big JavaScript project. It helps me with type issues, organizing code and maintainability. You should really give it a try!