Debounce

91.8% acceptance

Mar 2, 2026

481

Given a function fn and a time in milliseconds t, return a debounced version of that function. A debounced function is a function whose execution is delayed by t milliseconds and whose execution is cancelled if it is called again within that window of time. The debounced function should also receive the passed parameters. For example, let's say t = 50ms, and the function was called at 30ms, 60ms, and 100ms. The first 2 function calls would be cancelled, and the 3rd function call would be executed at 150ms. If instead t = 35ms, The 1st call would be cancelled, the 2nd would be executed at 95ms, and the 3rd would be executed at 135ms. The above diagram shows how debounce will transform events. Each rectangle represents 100ms and the debounce time is 400ms. Each color represents a different set of inputs. Please solve it without using lodash's _.debounce() function.

Solution

TypeScript

Time O(1)

Space O(1)

LeetCode

solution.ts

type F = (...args: number[]) => void;

function debounce(fn: F, t: number): F {
  let timer: ReturnType<typeof setTimeout> | null = null;
  return function (...args: number[]) {
  if (timer !== null) clearTimeout(timer);
  timer = setTimeout(() => {
    fn(...args);
    timer = null;
  }, t);
  };
}

/**
 * const log = debounce(console.log, 100);
 * log('Hello'); // cancelled
 * log('Hello'); // cancelled
 * log('Hello'); // Logged at t=100ms
 */