的摘要循环异步吗？

Question

I have the following piece of code:

$scope.$apply(function () {
    $scope.$emit("connectionadd.flowchart", data);
});

if (data.cancel) {
    return false;
} else {
    return true;
}

I'm wondering whether the execution can reach if (data.cancel) line before everything inside $scope.$apply callback is executed? If $digest is async, than it's possible.

Answer 1

No its not, pseudo code:

function $apply(expr) {
  try {
    return $eval(expr);
  } catch (e) {
    $exceptionHandler(e);
  } finally {
    $root.$digest();
  }
}

So the answer is that it will not reach if (data.cancel) before completing, although it is possible to make that happen with $scope.$applyAsyncc

$digest is also not async, but even it was purely by answering your question, then callback still would be executed before, because digest is called after the callback execution.

You can review $digest code here: https://github.com/angular/angular.js/blob/master/src/ng/rootScope.js