diff options
| -rw-r--r-- | src/ng/rootScope.js | 32 |
1 files changed, 32 insertions, 0 deletions
diff --git a/src/ng/rootScope.js b/src/ng/rootScope.js index 58aedd05..8be495db 100644 --- a/src/ng/rootScope.js +++ b/src/ng/rootScope.js @@ -240,6 +240,8 @@ function $RootScopeProvider(){ * can compare the `newVal` and `oldVal`. If these two values are identical (`===`) then the * listener was called due to initialization. * + * The example below contains an illustration of using a function as your $watch listener + * * * # Example * <pre> @@ -261,6 +263,36 @@ function $RootScopeProvider(){ scope.name = 'adam'; scope.$digest(); expect(scope.counter).toEqual(1); + + + + // Using a listener function + var food; + scope.foodCounter = 0; + expect(scope.foodCounter).toEqual(0); + scope.$watch( + // This is the listener function + function() { return food; }, + // This is the change handler + function(newValue, oldValue) { + if ( newValue !== oldValue ) { + // Only increment the counter if the value changed + scope.foodCounter = scope.foodCounter + 1; + } + } + ); + // No digest has been run so the counter will be zero + expect(scope.foodCounter).toEqual(0); + + // Run the digest but since food has not changed cout will still be zero + scope.$digest(); + expect(scope.foodCounter).toEqual(0); + + // Update food and run digest. Now the counter will increment + food = 'cheeseburger'; + scope.$digest(); + expect(scope.foodCounter).toEqual(1); + * </pre> * * |