Given this code:
Give your form a name:
So you can access your form validation status on your scope.
app.controller('MyCtrl', function($scope) {
$scope.myForm.$valid // form valid or not
$scope.myForm.myInput // input valid or not
// do something with myForm, e.g. display a message manually
})
angular doc
There is no way to trigger browser form behavior outside of a form. You have to do this manually.