AI solution for JavaScript Coding Question on BFE.dev
72. implement Observable interval()

Solution:

function interval(duration) {
  let count = 0;
  return new Observable(observer => {
    const intervalId = setInterval(() => {
      observer.next(count++);
    }, duration);
    return () => {
      clearInterval(intervalId);
    }
  });
}

We first declare a count variable which will keep track of the sequential numbers emitted by the Observable. Then, we return a new Observable with a function that takes an observer as an argument. We use setInterval() to emit the sequential numbers every duration seconds and pass them to the observer using observer.next(). We also return a clean-up function to clear the interval using clearInterval() when the observer unsubscribes.