No idea why this is broken.

cameragrid.js

@@ -15,9 +15,20 @@ limitations under the License.
 */
 var cameraGrid = {};
 
+/**
+ * @callback getUrl
+ * @param {String} sourceUrl Base URL of the camera
+ * @param {number} width Valid resolution width in pixels
+ * @param {number} height Valid resolution height in pixels
+ */
+
 /**
  * @constructor
  * @export
+ * @param {Node} container DOM container object to hold UI
+ * @param {String[]} sourceUrls Array of Axis camera URLs
+ * @param {number[][]=} resolutions Array of [width,height] resolution tuples
+ * @param {getUrl=} getUrl Callback to generate URL for a given camera
  */
 cameraGrid.CameraGrid = function(container, sourceUrls, resolutions, getUrl) {
   this.container_ = container;
@@ -87,7 +98,7 @@ cameraGrid.CameraGrid.prototype.setSelectedNoScan_ = function(index) {
 };
 
 cameraGrid.CameraGrid.prototype.setSelected_ = function(index) {
-  var old_index;
+  var old_index = null;
 
   if (this.selected_ == index) {
     this.removeCSSClass_(this.cells_[this.selected_], 'cameraGridFullScreen');