It has evolved from a browser only scripting language to a standard which has found acceptance as a tool for desktop development in the form of Electron, mobile development in the form of Xamarin and Cardova.
For a short time it was a supported option to develop full fledged games using Unity game engine. Node JS has been accepted as a full fledged web server which can be used to host mission critical websites.
Typically Testing is classified as
Automated testing is a set of technical scripts that can be run repeatedly at any time of day.When a software tester manually checks a system, he can make a mistake, especially when an application contains hundreds to thousands of lines of code. Automation helps the QA team avoid these human errors in application testing and executes checks in a faster time frame than if it were done in person.
Being popular, millions of libraries have come up to add features to this basic runtime. Some of them like express have become very popular and almost a standard when developing applications on Node server.