>It's a built-in angular function - just call it.....

It's not working in this particular form :( E.g. I changed the directive to be now

app.directive('noDirtyCheck', [function () {
        // Interacting with input elements having this directive won't cause the
        // form to be marked dirty.
        // http://stackoverflow.com/questions/17089090/prevent-input-from-setting-form-dirty-angularjs
        return {
            restrict: 'A',
           
            require: 'ngModel',
            link: function (scope, element, attrs, ctrl) {                           

                element[0].focus(function () {
                    ctrl.$setPristine();
                });

                //element[0].onblur(function () {
                //    ctrl.$setPristine();
                //});
            }
        };
    }]);

and the control defined as

<input class="form-control ng-valid ng-dirty ng-valid-parse ng-touched" type="text" ng-model="searchTerm" name="searchTerm" id="searchTerm" data-no:dirty-check="" placeholder="Search">

(this is what I see when I inspect the element).

In the HTML it's defined as

<div class="col-lg-5 col-lg-offset-1">
                <input class="form-control" type="text" ng-model="searchTerm" 
                name="searchTerm" id="searchTerm"
                data-no:dirty-check
                       placeholder="@Labels.search" />
            </div>

The directive seems to work fine in another form and it's not working in this form. These things are driving me crazy :(