Debounce function; based heavily on underscore's but updated for ES6

debounce.js

// Returns a function, that, as long as it continues to be invoked, will not
// be triggered. The function will be called after it stops being called for
// N milliseconds. If `immediate` is passed, trigger the function on the
// leading edge, instead of the trailing.

const debounce = function(func, wait, immediate) {
  let timeout;

  return function(...args) {

    const later = function() {
      timeout = null;
      if (!immediate) Reflect.apply(func, this, args);
    };

    const callNow = immediate && !timeout;

    clearTimeout(timeout);
    timeout = setTimeout(later, wait);
    if (callNow) Reflect.apply(func, this, args);
  };
};

module.exports = debounce;