Creates an angular 1.x directive to remove non-numerical input from input fields

numbersOnlyDirective.ts

directives.directive('intergenNumbersOnly', () => {
    'use strict';
    return {
        require: 'ngModel',
        link: (scope, element, attrs, modelCtrl) => {
            modelCtrl.$parsers.push(inputValue => {
                if (inputValue === undefined) {
                    return '';
                }

                var transformedInput = inputValue.replace(/[^0-9]/g, '');
                if (transformedInput !== inputValue) {
                    modelCtrl.$setViewValue(transformedInput);
                    modelCtrl.$render();
                }
                return transformedInput;
            });
        }
    };
});