JavaScript is easy to debug and test, its relative safe, and closures makes it easy to write async programs. Compared to C or C++ you'll have a huge productivity boost with a very small performance penalty. It's also easy to learn compared to other languages. It also doesn't have a standard library which makes it easy to integrate into any platform. For example in Windows OS and other Microsoft products you've been able to use JavaScript as a scripting language for a very long time. So JavaScript is not a language that has only been available in browsers. There are actually people out there that prefer JavaScript and write in it voluntarily.