AngularJS Live Example

HTML

<script src="http://code.angularjs.org/angular-1.0.0rc5.min.js"></script>
<div ng-app="HelloApp">
    <div ng-controller="MyCtrl">
        <input type="text" ng-model="box1" ng-keydown ="validatebox($event)">
    </div>
</div>

JavaScript

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


app.controller('MyCtrl',['$scope','$element', function($scope, $element) {


    $scope.box1 = 20;

    $scope.validatebox = function (e){
         
      var element = e.target;
      var element_val = $(element).val();
      element_val = parseInt(element_val);
      
        var reg = /^[1-9][0-9]?$|^100$/; 
           if(reg.test(element_val) === false)//validate
             {
              e.preventDefault();
            return;
            }
         
     };


    
}]);