first - 3
RxJS 5 first
HTML
<script src="https://npmcdn.com/@reactivex/[email protected]/dist/global/Rx.umd.js"></script>JavaScript
const source = Rx.Observable.from([1,2,3,4,5]);
//using optional projection function
const example = source.first(num => num % 2 === 0,
(result, index) => `First even: ${result} is at index: ${index}`);
//output: "First even: 2 at index: 1"
const subscribe = example.subscribe(val => console.log(val));