currency directive

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/angular.js/1.6.5/angular.min.js"></script>
<div ng-controller="MyCtrl">
  <div>Raw Value: {{currencyVal}}</div>

  <input type='text' number-input ng-model="currencyVal">
</div>

JavaScript

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

myApp.controller('MyCtrl', function($scope) {
  $scope.currencyVal = 123456;
});

// adds commas to numbers as they are entered into an input 
// allows negative numbers and a decimal. Good idea to use this with an input type="tel"
// in cases where the number does not need to be negative or a decimal
// so that smartphone browsers bring up number keyboard, but also will allow for commas.
// otherwise must use input type="text". accepts data-integer and data-positive attributes
myApp.directive('numberInput', function($filter) {
  return {
    require: 'ngModel',
    link: function(scope, elem, attrs, ngModelCtrl) {

      ngModelCtrl.$formatters.push(function(modelValue) {
        return setDisplayNumber(modelValue, true);
      });

      // it's best to change the displayed text using elem.val() rather than
      // ngModelCtrl.$setViewValue because the latter will re-trigger the parser
      // and not necessarily in the correct order with the changed value last.
      // see http://radify.io/blog/understanding-ngmodelcontroller-by-example-part-1/
      // for an explanation of how ngModelCtrl works.
      ngModelCtrl.$parsers.push(function(viewValue) {
        setDisplayNumber(viewValue);
        return setModelNumber(viewValue);
      });

      // occasionally the parser chain doesn't run (when the user repeatedly 
      // types the same non-numeric character)
      // for these cases, clean up again half a second later using "keyup"
      // (the parser runs much sooner than keyup, so it's better UX to also do it within parser
      // to give the feeling that the comma is added as they type)
      elem.bind('keyup focus', function() {
        setDisplayNumber(elem.val());
      });

      function setDisplayNumber(val, formatter) {
        var valStr, displayValue;

        if (typeof val === 'undefined') {
          return 0;
        }

        valStr = val.toString();
        displayValue =...