Angular directive to capitalize letters and ignore numbers

I have the following Angular directive that should capitalize the input and also reject any characters that are not English alphabet characters:

<input type="text" maxlength="1" capitalize />


.directive('capitalize', function() {
  return {
    require: 'ngModel',
    link: function(scope, element, attrs, modelCtrl) {
      var capitalize = function(inputValue) {
        if (inputValue == undefined) inputValue = '';

        inputValue = inputValue.replace(/[^a-zA-Z]/g, ''); //to reject non-alphabet characters
        var capitalized = inputValue.toUpperCase();
        if (capitalized !== inputValue) {
          modelCtrl.$setViewValue(capitalized);
          modelCtrl.$render();
        }
        return capitalized;
      }
      modelCtrl.$parsers.push(capitalize);
      capitalize(scope[attrs.ngModel]); // capitalize initial value
    }
  };
})

It does capitalize the input, but does NOT reject non-alphabet characters. Suggestions?

Store your updated input value after removing special charters in a separate variable, and then capitalize it, so that the capitalized updated input value can be compared from the original value.

 var charString = inputValue.replace(/[^a-zA-Z]/g, ''); //to reject non-alphabet characters
 var capitalized = charString.toUpperCase();

updated JSFiddle here: http://jsfiddle.net/p149wuL1/3/ I hope this helps