Function throttle

throttle<T extends (...args: unknown[]) => unknown>(
func: T,
wait: number,
): DebouncedFunction<T>

Creates a throttled function that invokes func at most once per wait milliseconds.

Type Parameters

T extends (...args: unknown[]) => unknown
The function type to throttle.

Parameters

func: T
The function to throttle.
wait: number
Milliseconds to throttle invocations to.

Returns DebouncedFunction<T>

Throttled function with optional cancel method.

Source

export function throttle<T extends (...args: unknown[]) => unknown>(
  func: T,
  wait: number,
): DebouncedFunction<T> {
  let timeoutId: ReturnType<typeof setTimeout> | null = null;
  let lastArgs: Parameters<T> | null = null;

  function throttled(...args: Parameters<T>): void {
    lastArgs = args;

    if (timeoutId === null) {
      func(...args);
      timeoutId = setTimeout(() => {
        if (lastArgs !== null) {
          func(...lastArgs);
        }
        timeoutId = null;
        lastArgs = null;
      }, wait);
    }
  }

  throttled.cancel = (): void => {
    if (timeoutId !== null) {
      clearTimeout(timeoutId);
      timeoutId = null;
      lastArgs = null;
    }
  };

  return throttled;
}