Lightbulb1 Lightbulb1 - 3 months ago 48
AngularJS Question

AngularJS : Prevent error $digest already in progress when calling $scope.$apply()

I'm finding that I need to update the my page to my scope manually more and more since building an application in angular.

The only way I know of to do this is to call

$apply()
from the scope of my controllers and directives. The problem with this is that it keeps throwing an error to the console that reads :


Error: $digest already in progress


Does anyone know how to avoid this error or achieve the same thing but a different way?

Lee Lee
Answer

Don't use this pattern - This will end up causing more errors than it solves. Even though you think it fixed something, it didn't.

You can check if a $digest is already in progress by checking $scope.$$phase.

if(!$scope.$$phase) {
  //$digest or $apply
}

$scope.$$phase will return "$digest" or "$apply" if a $digest or $apply is in progress. I believe the difference between these states is that $digest will process the watches of the current scope and it's children, and $apply will process the watchers of all scopes.

To @dnc253's point, if you find yourself calling $digest or $apply frequently, you may be doing it wrong. I generally find I need to digest when I need to update the scope's state as a result of a DOM event firing outside the reach of Angular. For example, when a twitter bootstrap modal becomes hidden. Sometimes the DOM event fires when a $digest is in progress, sometimes not. That's why I use this check.

I would love to know a better way if anyone knows one.


From comments: by @anddoutoi

angular.js Anti Patterns

  1. Don't do if (!$scope.$$phase) $scope.$apply(), it means your $scope.$apply() isn't high enough in the call stack.