expand

RxJS 5 expand

by Echyzen

HTML

<script src="https://npmcdn.com/@reactivex/[email protected]/dist/global/Rx.umd.js"></script>
<script src="https://rawgit.com/eu81273/jsfiddle-console/master/console.js"></script>

JavaScript

//emit 2
const source = Rx.Observable.of(2);
const example = source
  //recursively call supplied function
  .expand(val => {
       //2,3,4,5,6
       console.log(`Passed value: ${val}`);
       //3,4,5,6
       return Rx.Observable.of(1 + val);
    })
  //call 5 times
  .take(5);
/*
	"RESULT: 2"
	"Passed value: 2"
	"RESULT: 3"
	"Passed value: 3"
	"RESULT: 4"
	"Passed value: 4"
	"RESULT: 5"
	"Passed value: 5"
	"RESULT: 6"
	"Passed value: 6"
*/
//output: 2,3,4,5,6
const subscribe = example.subscribe(val => console.log(`RESULT: ${val}`));