JavaScript Interview Question #121

What is throttling?

Closures, Prototypes, Classes & Advanced Functions Mid-Level Intermediate

Quick Interview Answer

Throttling limits how frequently a function can execute during a period of continuous calls. Unlike debouncing, throttling can continue producing results at controlled intervals while the activity is still happening.

Detailed Explanation

It is useful for scroll, pointer-move, resize, and similar high-frequency events when periodic updates are required but executing on every event would be too expensive.

Code Example

function throttle(fn, delay) {
    let allowed = true;

    return (...args) => {
        if (!allowed) return;

        allowed = false;
        fn(...args);

        setTimeout(() => {
            allowed = true;
        }, delay);
    };
}

const onScroll = throttle(
    () => console.log("Scroll handled"),
    200
);