simple observable creation

new-obs.js

//import RxJS5
const Rx = require('rxjs');

// create an observable
// An observable is: "just a function that takes a subscriber and returns a function"

const obs = Rx.Observable.create(sub => {
  
       const to = setTimeout(() => {
        // do some work
        // then fire the following *callbacks*
        sub.next();
        //if we are one and done, then fire complete()
        sub.complete();
       }, 200);
  
     return function unsubscribe(){
        // if we unsubscribe from this observable before the timeout fires
        // this function is invoked, essentially the purpose is for cleanup
        clearTimeout(to); 
     }
  
});