JavaScript

Undoubtedly, JavaScript is the language that generates less friction between the frontend and backend, as the backend JavaScript is optional, and the frontend is practically mandatory. It is a language with a good level of complexity. The developer needs to know the internal behavior of JavaScript well to not make bizarre mistakes. The paradigm that best applies to JavaScript is functional. The ecosystem has vast frameworks, too many in some cases, generating complexity especially regarding the builds. It has good performance, but it requires good proficiency to maintain the code and write new features.