title: Uncaught TypeError: Cannot call method 'addEventListener' of undefined
body: <p>can't figure out where is the error in this code. Chrome debug console keep saying "Uncaught TypeError: Cannot call method 'addEventListener' of undefined" at line 31!</p>
  
  <pre><code>jewel.dom = (function() {
  
      var $ = Sizzle;
  
      function hasClass(el, clsName){
  
          var regex = new RegExp("(^|\\s) + clsName + (\\s|$)");
          return regex.test(el.className);
      }
  
      function addClass(el, clsName) {
  
          if (!hasClass(el,clsName)) {
              el.className += ""+ clsName;
          }
      }
  
      function removeClass (el, clsName) {
  
          var regex = new RegExp("(^|\\s)" + clsName + "(\\s|$)");
          el.className = el.className.replace(regex, " ");
      }
  
      function bind(element, event, handler) {
  
          if (typeof element == "string") {
              element = $(element)[0];
          }
  
          element.addEventListener(event, handler, false)
  }
  
      return {
          $:$,
          hasClass : hasClass,
          addClass : addClass,
          removeClass : removeClass,
          bind : bind
      };
  ;}) ();
  </code></pre>