Show an error when inputs match

nomatch.css

.help-block {
    display: none;
}
.has-error .help-block {
    display: block;
}

nomatch.html

<form name="myForm">
  <input name="mobile1" ng-model="mobile.first" />
  <input name="mobile2" ng-model="mobile.second" />
  <p ng-if="myForm.mobile2.$error.mismatch && myForm.mobile2.$dirty" class="help-block">First Mobile and Second Mobile must NOT match.</p>
</form>

nomatch.js

angular.module('myapp')
  .directive('notmatch', function($parse) {
    return {
      require: 'ngModel',
      link: function(scope, elem, attrs, ctrl) {
        scope.$watch(function() {
          return $parse(attrs.notmatch)(scope) === ctrl.$modelValue;
        }, function(currentValue) {
          ctrl.$setValidity('mismatch', !currentValue);
        });
      }
    };
  });