title: My function() won't run?
body: <p>With this function I am trying to show a lightbulb that switches on and off once the user clicks it.</p>
  
  <pre><code>(function () {
      var FavData, ImageData, create_zip, fav, favData;
  
      window.imageData = [];
  
      saveButton = document.createElement("save_button");
      saveButton.innerHTML = "save_button";
      saveButton.onclick = function () {
          var image = document.getElementById('save_button');
          if (image.src.match("http://www.w3schools.com/js/pic_bulbon.gif")) {
              image.src = "http://www.w3schools.com/js/pic_bulboff.gif";
          } else {
              image.src = "http://www.w3schools.com/js/pic_bulbon.gif";
          }
      };
  }).call(this);
  </code></pre>
  
  <p>And my html:</p>
  
  <pre><code>&lt;button id="save_button"&gt;&lt;img src="image" width="100" height="180"&gt;&lt;/button&gt;
  </code></pre>
  
  <p>with the id "save_button".</p>