javascript - Input field not updating with ng-keydown event -

in piece of code want add validation input field, if value 0 don't know why not able update , enter new value in input field. not able change input field value.

value remain same if delete existing value , add in existing value.

here html code:

<input ng-model="lineitemdetailsctrlas.lineitems.orderedquantity" type="text" class="col-md-6 text-right panel-row-spacing"                 ng-keydown="valuechanged($event)" required                 /> 

and angular code is:

$scope.valuechanged = function (event) {  var quantityrequire={};     if (event.keycode === 48 || lineitemdetailsctrlas.lineitems.orderedquantity == 0) {             quantityrequire = {               "messageid": "ordered_quantity",               "params": [],               "severity": "error"             };             lineitemdetailsctrlas.errormessages.push(quantityrequire);           }           else{             event.preventdefault();           }     }; 

you stopping event "event.preventdefault();", because keycode 48 (only number 0) acceptable others keyevents falling down on else condition , stop updating input value.