RxJS is one of the latest libraries in web development. Offering a powerful, functional approach for dealing with events and with integration points into a growing number of frameworks, libraries, and utilities,

RxJS is a library for composing asynchronous and event-based programs by using observable sequences.

Observable Stream
    -   User Input
    -  Http Request
    -  Array
    -  Object
Observable Handle
   - Data
   - Error
   - Completion

We can handle observable through of subscribe with three methods data,error and complete,
       (data) => console.log(data),
       (error) => console.log(error),
       () => console.log("Complete")