@Vitalii-Korsakov Well, it's not a full-stack Linux environment. However, you can run Node.js on the Onion using the command:
opkg update
opkg install nodejs
Note, this version it will install is v0.10.5. The V8 engine is still unsupported in this architecture.
As far as getting node packages installed, it is best to install them on your host system (I run a Mac) and then copy them over to the Onion. My approach to this is to perform the install via NPM, zip the entire directory up and upload it to Dropdox. From there, I can perform a WGET on the Onion to retrieve the zip file.
Note that many if not all modules that have compiled binaries will not run on the Omega. If the module is strictly Javascript-based, then it should run no problem.