ReScript is one of several emerging programming languages that helps web developers build complex web applications that can be transpiled into JavaScript and run in the browser.

JavaScript usage has changed drastically over the past 25 years. However, while the language continues to evolve, it struggles to deliver the capabilities required for the complex applications that are being developed these days.

Languages like ReScript and TypeScript fill in the gaps that exist in JavaScript and help developers build more robust applications that can still run in the browser through JavaScript transpilation.

TypeScript quickly became the dominant player in the field by offering a convenient migration path from JavaScript that relies on the fact that TypeScript is a superset of JavaScript, meaning that code written in JavaScript is a valid TypeScript code – making the migration process as easy as renaming a file. Developers can slowly add TypeScript specific features  without requiring a complete rewrite of the application.

ReScript, on the other hand, only covers a subset of JavaScript, which enables it to keep a lean syntax that is easy to learn and is instrumental in helping developers avoid many of the pitfalls that JavaScript (and, therefore, TypeScript) includes.

This means that migrating to ReScript is more challenging. Still, ReScript code is generally easier to read and maintain, generates optimized, readable JavaScript code, and provides a fast compiler that is taught to be one or two orders of magnitude faster than alternatives.