Do things called in .then of a $q promise chain get applied in a digest?

Question

If I use Angular's $q, do I have to worry about using $evalAsyn or $apply? Or is that handled automatically by $q?

Answer 1

Commonly, you don't need to worry about the $digest/$apply/$evalSync things in angular. According to $q document here,

There is a short comparison:

Differences between Kris Kowal's Q and $q

There are two main differences:

• $q is integrated with the $rootScope.Scope Scope model observation mechanism in angular, which means faster propagation of resolution or rejection into your models and avoiding unnecessary browser repaints, which would result in flickering UI.
• Q has many more features than $q, but that comes at a cost of bytes. $q is tiny, but contains all the important functionality needed for common async tasks.

Here is the source code in $q.

this.$get = ['$rootScope', '$exceptionHandler', function($rootScope, $exceptionHandler) {
    return qFactory(function(callback) { //invoke qFactory
      $rootScope.$evalAsync(callback); //$evalAsync here...
    }, $exceptionHandler);
}];
function $$QProvider() {
  this.$get = ['$browser', '$exceptionHandler', function($browser, $exceptionHandler) {
    return qFactory(function(callback) {
      $browser.defer(callback);
    }, $exceptionHandler);
  }];
}