es6-debounce.js

export function debounce(func, wait, immediate) {
  let timeout;
  return function() {
    const later = () => {
      timeout = null;
      if (!immediate) func.apply(this, arguments);
    };
    const callNow = immediate && !timeout;
    clearTimeout(timeout);
    timeout = setTimeout(later, wait);
    if (callNow) func.apply(this, arguments);
  };
}