JavaScript has a dynamic type system. Haxe or a typescript is for developers who prefer static type system. It is statically typed and transpiles to JavaScript. The purpose of TypeScript is to provide compile-time type checking. You have to add immutableJS and its typing’s. you will have to write types in TypeScript. TypeScript is limited it cannot always offer a hand.

ReasonML is a syntax extension for OCaml language. In ReasonML immutable data is in the language. There are runtime validators. The ReasonML compilation is very fast. It supports native and JavaScript. Reasons’s type system is sound. The syntax of Reason is very simple and it is like javaScript.