Angular:

http://angularjs.org/

by scott_in_ct

HTML

<div ng-controller="MyCtrl">
    <label>Enter more numbers/characters to test:</label><br/>
    <input type="text" ng-model="thisNum" clean-field>
    <h3>thisNum is {{thisNum}}</h3>
</div>

JavaScript

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

myApp.directive('cleanField', function(uppercaseFilter) {
   return {
     require: 'ngModel',
     link: function(scope, element, attrs, modelCtrl) {
         var sanitize = function(inputValue) {
            var clean = "";
             if (inputValue) {
                 clean = inputValue.replace(/[^\d.]+/g, '');
                 if (clean != inputValue) {
                     modelCtrl.$setViewValue(clean);
                     modelCtrl.$render();
                 }
             }
             return clean;
         };
         modelCtrl.$parsers.push(sanitize);
         sanitize(scope[attrs.ngModel]); //runs on load
     }
   };
});

function MyCtrl($scope) {
    $scope.thisNum = '8asdf0';
}