Merge pull request #12 from Extensis/master

Performance: Adjust $watch statement so it does not run every $digest

src/nya-bootstrap-select.js

@@ -46,6 +46,8 @@ angular.module('nya.bootstrap.select',[])
           angular.forEach(BS_ATTR, function(attr) {
             selectorOptions[attr] = attrs[attr];
           });
+
+          return selectorOptions;
         };
 
         /**
@@ -78,7 +80,7 @@ angular.module('nya.bootstrap.select',[])
           }
         };
 
-        scope.$watch(function optionDOMWatch(){
+        function optionDOMWatch(){
           // check every option if has changed.
           var optionElements = $(element).find('option');
 
@@ -112,8 +114,18 @@ angular.module('nya.bootstrap.select',[])
             }
             optionArray = makeOptionArray(optionElements);
           }
+        }
 
-        });
+        scope.$watch(function(){
+          // Create an object to deep inspect if anything has changed.
+          // This is slow, but not as slow as calling optionDOMWatch every $digest
+          return {
+            ngModel: ngCtrl.$viewValue,
+            options: makeOptionArray( $(element).find('option') ),
+            selectors: updateSelectorOptions()
+          };
+        // If any of the above properties change, call optionDOMWatch.
+        }, optionDOMWatch, true);
 
         var setValue = function(modelValue) {
           var collection = valuesFn(scope);