AngularJS Form Reset Directive (Multiple Models)

A directive that supports the native reset button type in AngularJS forms with multiple models.

HTML

<div ng-controller="MyCtrl">
    <form reset-directive="myModel myOtherModel" name="form">
        <input type="text" ng-model="myModel.foo" />
        <input type="text" ng-model="myOtherModel.foo" />
        <input type="reset" value="eset" />
        <pre>myModel: {{ myModel | json }}</pre>
        <pre>myOtherModel: {{ myOtherModel | json }}</pre>
        <pre>form pristine: {{ form.$pristine }}</pre>
    </form>
</div>

JavaScript

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

myApp.controller( 'MyCtrl', [ '$scope', function ( $scope ) {
    $scope.myModel = { foo: 'Boop' };
    $scope.myOtherModel = { foo: 'Beep' };
}]);

myApp.directive( 'resetDirective', [ '$parse', function ( $parse ) {
    return function( scope, element, attr ) {
        var fns = map( attr.resetDirective.split( /(?:,? |,)/ ), function ( model ) {
            var fn = $parse( model );

            // Error check to see if expression returned a model
            if ( !fn.assign ) {
                throw Error( 'Expression is required to be a model: ' + model );
            }

            return fn;
        });
        var masterModels = map( fns, function ( fn ) {
            return angular.copy( fn( scope ) );
        });

        element.bind( 'reset', function ( event ) {
            scope.$apply( function () {
                fns.forEach( function ( fn, i ) {
                    fn.assign( scope, angular.copy( masterModels[ i ] ) );
                });

                scope.form.$setPristine();
            });

            // TODO: memoize prevention method
            if ( event.preventDefault ) {
                return event.preventDefault();
            }
            else {
                return false;
            }
          });
      };
}]);

function map( obj, iterator, context ) {
    var results = [];

    angular.forEach( obj, function( value, index, list ) {
        results.push(
            iterator.call( context, value, index, list )
        );
    });

    return results;
}