How often does angular js poll functions passed under $watch

Question

If I were to create a $watch expression like:

         $scope.$watch(function(){
              return(MyDataStore.someInstanceVariable);}
          , function(newVal, oldVal){
               $scope.scopeVariable = newVal;}
          , true)

How often would this function execute? How often would it poll the data store? Just how (in)efficient is this approach?

It would poll the data store at least as many times as there are $digest loops. Read [Databinding in angularjs](http://stackoverflow.com/questions/9682092/databinding-in-angularjs) — Stewie, Jun 19 '13 at 05:30

score 1 · Accepted Answer · answered Jun 19 '13 at 05:32

From the angularjs docs:

The watchExpression is called on every call to $digest() and should return the value which will be watched. (Since $digest() reruns when it detects changes the watchExpression can execute multiple times per $digest() and should be idempotent.)

See the docs at: Angularjs Watch

How often does angular js poll functions passed under $watch

1 Answers1