javascript - RxJs: distinctUntilChanged still emits duplicate values -

i have stream of values limit using lower , upper bound, , decrease amount of logging emit values if change. problem second distinctuntilchanged() in following snippet still produces duplicates:

observable // emits i.e. [2, 2, 2, 5, 5, 10, 20] .distinctuntilchanged() // becomes [2, 5, 10, 20] .map(target => {   const correctedtarget = math.min(math.max(target, minimum), maximum); // let's min: 5, max: 10   if(correctedtarget != target) {     logger.warn(`prediction wants scale out-of-bounds ${target}, limiting ${correctedtarget}`);   }   return correctedtarget; }) // becomes [5, 5, 10, 10] .distinctuntilchanged() // should [5, 10], [5, 5, 10, 10] 

the rxjs docs state filter defaults simple equality comparison, i'd expect should work™.

one of colleagues (once again) identified problem (also matt). turns out initial assumption wrong - outline of code follows:

observable // emits credentials on interval .flatmap(credentials => {   return observable2.dosomething()          .distinctuntilchanged()          ... }) 

as can see, distinctuntilchanged chained observable2, new observable stream every time credentials emitted. explains why comparator function made doesn't called @ all: there 1 value every time there nothing compare to.