There are following four folders. In each folder, server can be run by either running "run_server.bat" file or by running command "node server" in cmd. After running server, access this url: http://localhost:3000/I/want/title/?address=google.com&address=www.dawn.com/events/ to check the code
implemented task using plain node.js callbacks.
implemented task using step.js library.
implemented task using promise.
implemented task using rxjs observable.