Moved internal functions in Images.load onto the prototype

Added comments to Images.js

lib/network/Images.js

@@ -10,58 +10,87 @@ function Images(callback) {
 }
 
 /**
- *
- * @param {string} url          Url of the image
- * @param {string} url          Url of an image to use if the url image is not found
- * @return {Image} img          The image object
+ * @param {string} url                      The Url to cache the image as 
+  * @return {Image} imageToLoadBrokenUrlOn  The image object
  */
-Images.prototype.load = function (url, brokenUrl, id) {
-    var me = this;
-    
-    function addImageToCache(imageToCache) {
-        // IE11 fix -- thanks dponch!
-        if (imageToCache.width === 0) {
-            document.body.appendChild(imageToCache);
-            imageToCache.width = imageToCache.offsetWidth;
-            imageToCache.height = imageToCache.offsetHeight;
-            document.body.removeChild(imageToCache);
-        }
-    
-        me.images[url] = imageToCache;
-    }
-    
-    function redrawWithImage(imageToRedrawWith) {
-        if (me.callback) {
-            me.callback(imageToRedrawWith);
-        }
+Images.prototype._addImageToCache = function (url, imageToCache) {
+    // IE11 fix -- thanks dponch!
+    if (imageToCache.width === 0) {
+        document.body.appendChild(imageToCache);
+        imageToCache.width = imageToCache.offsetWidth;
+        imageToCache.height = imageToCache.offsetHeight;
+        document.body.removeChild(imageToCache);
     }
+
+    this.images[url] = imageToCache;
+}
+
+/**
+ * @param {string} url                      The original Url that failed to load, if the broken image is successfully loaded it will be added to the cache using this Url as the key so that subsequent requests for this Url will return the broken image
+ * @param {string} brokenUrl                Url the broken image to try and load
+ * @return {Image} imageToLoadBrokenUrlOn   The image object
+ */
+Images.prototype._tryloadBrokenUrl = function (url, brokenUrl, imageToLoadBrokenUrlOn) {
+    //Store the instance of the Images object so that we can reference it in events
+    var self = this;
     
-    function tryloadBrokenUrl(imageToLoadBrokenUrlOn) {
-        if (brokenUrl === undefined) return;
+    //If any of the parameters aren't specified then exit the function because nothing constructive can be done
+    if (url === undefined || brokenUrl === undefined || imageToLoadBrokenUrlOn === undefined)  return;
+
+    //Clear the old subscription to the error event and put a new in place that only handle errors in loading the brokenImageUrl
+    imageToLoadBrokenUrlOn.onerror = function() {
+        console.error("Could not load brokenImage:", brokenUrl);
+        //Add an empty image to the cache so that when subsequent load calls are made for the url we don't try load the image and broken image again
+        self._addImageToCache(url, new Image());
+    };
     
-        imageToLoadBrokenUrlOn.onerror = function() {
-            console.error("Could not load brokenImage:", brokenUrl);
-            addImageToCache(new Image());
-        };
-        imageToLoadBrokenUrlOn.src = brokenUrl;
+    //Set the source of the image to the brokenUrl, this is actually what kicks off the loading of the broken image
+    imageToLoadBrokenUrlOn.src = brokenUrl;
+}
+
+/**
+ * @return {Image} imageToRedrawWith The images that will be passed to the callback when it is invoked
+ */    
+Images.prototype._redrawWithImage = function (imageToRedrawWith) {
+    if (this.callback) {
+        this.callback(imageToRedrawWith);
     }
+}    
+
+/**
+ * @param {string} url          Url of the image
+ * @param {string} brokenUrl    Url of an image to use if the url image is not found
+ * @return {Image} img          The image object
+ */
+Images.prototype.load = function (url, brokenUrl, id) {
+    //Store the instance of the Images object so that we can reference it in events
+    var self = this;
     
+    //Try and get the image from the cache, if successful then return the cached image   
     var cachedImage = this.images[url]; 
     if (cachedImage) return cachedImage;
     
+    //Create a new image
     var img = new Image();
+    
+    //Subscribe to the event that is raised if the image loads successfully 
     img.onload = function() {
-        addImageToCache(img);
-        redrawWithImage(img);
+        //Add the image to the cache and then request a redraw
+        self._addImageToCache(url, img);
+        self._redrawWithImage(img);
     };
     
+    //Subscribe to the event that is raised if the image fails to load
     img.onerror = function () {
         console.error("Could not load image:", url);
-        tryloadBrokenUrl(img);
+        //Try and load the image specified by the brokenUrl using
+        self._tryloadBrokenUrl(url, brokenUrl, img);
     }
     
+    //Set the source of the image to the url, this is actuall what kicks off the loading of the image
     img.src = url;
     
+    //Return the new image
     return img;
 };