Single, race both get only one emit value from the stream.

 

Single(fn):

const source = Rx.Observable.from([1,2,3,4,5]);var single = source.single( x => x === 3);/*(12345)|                   (source)single( x => x === 3)3|                         (single)*/var sub = single.subscribe( x =>  console.log(x)); // 3

 

race(...observable): Observable

const winner = Rx.Observable.race(  //emit every 1.5s  Rx.Observable.interval(1500),  //emit every 1s  Rx.Observable.interval(1000).mapTo('1s won!'),  //emit every 2s  Rx.Observable.interval(2000),  //emit every 2.5s  Rx.Observable.interval(2500)).take(1);/**------0                 (1500)----0                   (1000).mapTo('1s won!')--------0               (2000)----------0             (2500)race----(1s won!)|          (take(1))*/const sub2 = winner.subscribe( x => console.log(x)); // 1s won!