- You can use it in the server. Node.js and plenty of its frameworks are increasing in number and helping JS developers become full-stack developers.
- You can use it for mobile apps. Using Cordova and frameworks like Ionic or NativeScript, you can build mobile apps faster without the need to know native development in Java or Swift/Objective-C. You can even share the source code between mobile platforms.
- You can build IoT. SitePoint has published some articles by Patrick Catanzariti which can be very helpful for this purpose.