A custom Rxjs operator that takes the source observable and repeats the latest value on an interval while waiting for the new values to arrive.

repeatLatestOnInterval.js

// Usage:- https://replit.com/@Vikasg7/repeatLatestOnInterval
// Clojure version:- https://github.com/Vikasg7/clj-snake/blob/main/src/clj_snake/utils.clj
const repeatLatestOnInterval = (delayInMS) => (source) =>
  new Observable((observer) => {
    let id = null

    const next = (value) => {
      observer.next(value) // sending downstream
      clearTimeout(id)
      id = setTimeout(next, delayInMS, value)
    }
    
    const error = (err) => {
      clearTimeout(id)
      observer.error(err)
    }
    
    const complete = () => {
      clearTimeout(id)
      observer.complete()
    }
    
    return source.subscribe({next, error, complete})
  })