bookmarklet.js

(function() {
  function getScript(url) {
    var script = document.createElement('script');
    script.src = url;
    var head = document.getElementsByTagName('head')[0], done = false;
    script.onload = script.onreadystatechange = function() {
      if ( !done && (!this.readyState
           || this.readyState == 'loaded'
           || this.readyState == 'complete') ) {
        done=true;
        script.onload = script.onreadystatechange = null;
        head.removeChild(script);
      }
    };
    head.appendChild(script);
  }
  
  if(typeof window.Zepto == 'undefined') getScript('https://cdnjs.cloudflare.com/ajax/libs/zepto/1.0/zepto.min.js');
  if(typeof window._ == 'undefined') getScript('https://cdnjs.cloudflare.com/ajax/libs/lodash.js/1.1.1/lodash.min.js');
})();