CODEWITHSUNDEEP
javascriptrxjs
Christian
Christian

Reputation: 859

RXJS steam with distinct and throttleTime

I need help to create a RXJS stream which does the following.

Input: Keyboard inputevent a to z Emit value if:

Marble diagram (- is 1 second):

Input:  [aaa--b--b--aa--a-c-->
Output: [a----b-----a-----c-->

Upvotes: 1

Views: 58

Answers (1)

Ingo Bürk
Ingo Bürk

Reputation: 20043

You can group your input by character using groupBy. We can then grab the first occurrence in each group and finally merge everything back. As luck would have it, groupBy lets us define a duration selector to specify how long a group should live, so if we set that to 5 seconds, we basically "reset" each group after that time:

const source$ = fromEvent(document, 'keydown').pipe(
  map((evt: KeyboardEvent) => evt.key)
);

source$.pipe(
  // create one group per character, with each
  // group living for only up to 5 seconds
  groupBy(key => key, undefined, () => timer(5000)),

  // From each group, only take the first element
  map(group$ => group$.pipe(first())),

  // put everything back together
  mergeAll()
)

Upvotes: 2

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