Debounce Function in Typescript

debounce.test.ts

import { debounce } from './debounce';

describe('Debounce', () => {
  it('should test debounce', () => {
    jest.useFakeTimers();
    const oneSecond = 1000;
    const obj = {
      foo: 'foo',
      bar: 'bar',
    }
    const setFooDebounced = debounce((newFoo) => {
      obj.foo = newFoo;
    }, oneSecond);

    setFooDebounced('foo2')
    expect(obj.foo).toEqual('foo');
    setFooDebounced('foo3')
    jest.advanceTimersByTime(oneSecond);
    expect(obj.foo).toEqual('foo3');
  })
})

debounce.ts

export function debounce<T extends (...args: any[]) => any>(func: T, delay: number) {
  let timeoutId: ReturnType<typeof setTimeout>;
  return function (this: unknown, ...args: Parameters<T>) {
    if (timeoutId) {
      clearTimeout(timeoutId);
    }
    timeoutId = setTimeout(() => {
      func.apply(this, args);
      timeoutId = null;
    }, delay);
  } as T;
}