Demo:  sequenceEqual

The sequenceEqual verifies if the order of input items match to the order of the data specified.

It emits false as soon as as it receives a data item that does not match the given sequence.

sequenceEqual(observableToComparewith);

//Two different sources of data, emitted almost alternately
let input = iif(() => (Math.random()>0.5),
             of(50,15,20,30),
             of(50,15,20,10,30))
            .pipe(concatMap(v => of(v).pipe(delay(1000))));

//Emits true, if input sequence match, otherwise emits false.
let process = sequenceEqual(of(50, 15, 20, 30));

let output=input.pipe(process).subscribe(v=>console.log(v))