A typed throttle for Typescript.

throttle.ts

export function throttle<T extends (...args: any[]) => any>(
  fn: T,
  wait: number
) {
  let inThrottle: boolean, lastFn: any, lastTime: number

  return function(...a: Parameters<T>): ReturnType<T> {
    const context = this,
      args = arguments
    if (!inThrottle) {
      lastTime = Date.now()
      inThrottle = true
      return fn.apply(context, args)
    } else {
      clearTimeout(lastFn)
      lastFn = setTimeout(function() {
        if (Date.now() - lastTime >= wait) {
          lastTime = Date.now()
          return fn.apply(context, args)
        }
      }, Math.max(wait - (Date.now() - lastTime), 0))
    }
  }
}