在输入类型上添加文本输入

Question

我有这个代码对我有用，就是当我按下输入时，我用输入中的新文本替换文本，问题是如果不加以替换

<div ng-app="myApp" ng-controller="myCtrl as model">
     <input type="text"  ng-model="c1ero" ng-cero="uno" >   
     <input type="text"  ng-model="model.eae" ng-cero="dos" >   
    </div> 

angular
.module("myApp",[])
.controller('myCtrl', function($scope){
 var model=this;
})
.directive ('ngCero', function($parse){
  var linkFunction =function(scope, element, attrs){
     element.bind("keypress", function(event) {
         if(event.which === 13) {  
           scope.$apply(function(){
            scope.$eval(attrs.ngCero, {'event': event});
             $parse(attrs.ngModel).assign(scope, '0, ');
             console.log(attrs);
           });
           event.preventDefault(); 
         }
     });
  };
  return{
    //controller: "myCtrl",
    link: linkFunction
  }
}) 

和代码笔：http://codepen.io/fernandooj/pen/EgmQmJ