maxlengthDirective: (string | (($parse: any) => {
    require: string;
    restrict: string;
    link(scope: any, elm: any, attr: any, ctrl: any): void;
}))[] = ...

AngularJS expression that must evaluate to a Number or String parsable into a Number. Used as value for the maxlength ngModel.NgModelController#$validators validator.

ngMaxlength adds the maxlength ngModel.NgModelController#$validators validator to ngModel ngModel. It is most often used for text-based input input controls, but can also be applied to custom text-based controls.

The validator sets the maxlength error key if the ngModel.NgModelController#$viewValue ngModel.$viewValue is longer than the integer obtained by evaluating the AngularJS expression given in the ngMaxlength attribute value.

**Note:** This directive is also added when the plain `maxlength` attribute is used, with two differences:
  1. `ngMaxlength` does not set the `maxlength` attribute and therefore HTML5 constraint validation is not available.
  2. The `ngMaxlength` attribute must be an expression, while the `maxlength` value must be interpolated.