startWith - 2

RxJS 5 startWith

by Brian Troncone

HTML

<script src="https://npmcdn.com/@reactivex/[email protected]/dist/global/Rx.umd.js"></script>

JavaScript

//emit ('World!', 'Goodbye', 'World!')
const source = Rx.Observable.of('World!', 'Goodbye', 'World!');
//start with 'Hello', concat current string to previous
const example = source
  .startWith('Hello')
  .scan((acc, curr) => `${acc} ${curr}`);
/*
  output:
  "Hello"
  "Hello World!"
  "Hello World! Goodbye"
  "Hello World! Goodbye World!"
*/
const subscribe = example.subscribe(val => console.log(val));