Why should you care?

Scroll and resize fire hundreds of times per second; throttle keeps work manageable.

See it live — copy this example

Paste into an HTML file or the browser console (F12). Use Run below when the live editor is available.

function throttle(fn, ms) {
  let last = 0;
  return function (...args) {
    const now = Date.now();
    if (now - last >= ms) {
      last = now;
      fn.apply(this, args);
    }
  };
}

Run Example »

Edit the code below and click Run to see the result in Toolliyo’s live editor.

What happened?

• Unlike debounce, throttle fires during continuous events but spaced out.

Practice next

1. Run throttle helper and invoke rapidly.
2. Throttle scroll logger on window.
3. Compare behavior side-by-side with debounce lesson.
4. Throttle mousemove handler updating a tooltip position to 16ms.
5. Combine throttle with requestAnimationFrame for scroll sync.

Remember

Max once per interval Good for scroll/resize Different from debounce

ScriptVerse infinite feed

Scroll handler throttled to 100ms checks distance to bottom and loads next page.

Outcome: Throttling limits expensive scroll work while user is actively dragging.