Allow only characters in textbox using AngularJs

Hackish? way, $watch the ng-model in your controller:

<input type="text" ng-model="myText">

Controller:

$scope.$watch('myText', function() {
   // put logic to strip out all non-character characters here
   if ($scope.myText  ... regex to look for ... ) {
      // strip out the non-characters
   }
})

Best way, use a $parser in a directive. I'm not going to repeat the already good answer provided by @pkozlowski.opensource, so here's the link: https://stackoverflow.com/a/14425022/215945

Don't try to use ng-change -- it will cause problems. See AngularJS - reset of $scope.value doesn't change value in template (random behavior)

Update: ng-pattern can also be used to define a regex that will limit what is allowed in the field. See also the "cookbook" page about forms.