AngularJS - NumberFormat Directive for Phone Number/Date/Credit Card etc

<!DOCTYPE html>
<html>

<head>
  <script data-require="angular.js@1.4.8" data-semver="1.4.8" src="https://code.angularjs.org/1.4.8/angular.js"></script>
  <link rel="stylesheet" href="style.css" />
  <script src="script.js"></script>
</head>

<body ng-app='myApp' ng-controller='myController'>
  <label>Format: </label>
  <input type='text' ng-model='inputFormat' />
  <input type="button" value="Submit" ng-click="setFormat()" />
  <div>
    <samp>
      <br/>
    <label>Example:</label>
    <ul>
      <li>(___) ___ ____</li>
      <li>(___)-___-___</li>
      <li>___-___-____</li>
    </ul>
    </samp>
  </div>
  <div>

    <hr/>

    <strong ng-if='format'>Number format set to: {{format}}</strong>
    <strong ng-if='!format'>Please set the number format.</strong>
  </div>
  <br/>


  <label> Mobile #: </label>
  <input type='text' srik-net-number format='{{format}}' ng-model="inputText" />

</body>

</html>

// Code goes here

var myApp = angular.module('myApp', []);

myApp.controller('myController', ['$scope', function($scope) {
  $scope.setFormat = function() {
    $scope.format = $scope.inputFormat;
    $scope.inputText='';
  }
}]);

myApp.filter('numberFormat', function() {
  return function(format, input) {
    var lastChar;
    
    format=format||'(___)-___-____';

    if (!input) {
      return;
    }

    for (var index = 0; index < input.length; index++) {
      var char = input.charAt(index);
      if (parseInt(char)) {
        if (format.indexOf('_') >= 0) {
          format = format.replace('_', char);
          lastChar = char;
        }
      }
    }

    if (lastChar) {
      return format.substring(0, format.lastIndexOf(lastChar) + 1);
    }
  }
});

myApp.directive('srikNetNumber', ['$filter', function($filter) {
  return {
    resolve: 'A',
    replace: true,
    link: function(scope, ele, attrs) {
      var modelName = attrs.ngModel;

      scope.$watch(modelName, function(newValue, oldValue) {
        var formatValue = attrs.format;
        scope[modelName] = $filter('numberFormat')(formatValue, newValue);
      });
    }
  }
}]);

/* Styles go here */