JavaScript is the language of the browser. There's no denying that. Next, let's examine the reasons why a developer should pick Node.js as the back-end language for their application. Although there are many reasons, here we've boiled it down to two factors—context switching and shared code.
Context switching, or task switching, is when a developer is working on multiple projects, or in different languages, at the same time and has to switch between them regularly.
"Doing more than one task at a time, especially more than one complex task, takes a toll on productivity."
– Multitasking: Switching costs (American Psychological Association)