Answer

Throttling limits how frequently a function executes. A common leading-edge throttle runs immediately and ignores calls made during the configured interval.

function throttle(fn, delay) {
  let lastExecution = 0;

  return function (...args) {
    const now = Date.now();

    if (now - lastExecution >= delay) {
      lastExecution = now;
      return fn.apply(this, args);
    }
  };
}

const logScroll = throttle(() => {
  console.log("Scroll event handled");
}, 500);

window.addEventListener("scroll", logScroll);

Explanation

The wrapper records the time of the last execution. A new invocation executes only if the configured interval has passed.

This implementation is a basic leading-edge throttle. It does not schedule a trailing invocation, so the last event in a burst may never be processed. A production implementation may support both leading and trailing behavior, timer cleanup, and cancellation.