debounce.js

/**
 * Debounces (postpones) executing `func` until _at least_ `msWait` seconds have elapsed
 *  since the last time the same function had again been requested to execute.
 *
 * Example:
 *  const repaintElem = setRandomBgColorToElem(elem);
 *  document.addEventListener('resize', debounce(repaintElem, 10, true));
 *
 * @param {function} func The function to be debounced
 * @param {number} [msWait=50] The minimum amount of time in miliseconds to wait before executing `func`
 * @param {boolean} [execAsap=false] Whether the function should be called immediately the first time
 *
 * @returns {function} The function provided, debounced by the time provided in milliseconds
 */
export default (func, msWait = 50, execAsap = false) => {
  let timeout;

  return function debounced (...args) {
    function delayed () {
      if (!execAsap) {
        Reflect.apply(func, this, args);
      }
      timeout = undefined;
    }

    if (timeout) {
      clearTimeout(timeout);
    } else if (execAsap) {
      Reflect.apply(func, this, args);
    }

    timeout = setTimeout(delayed, msWait);
  };
};