AngularJS Simple Example

Input validation

HTML

<div ng-app ng-controller="LoginController">
    <div>Hello {{ user.firstName }}</div>
    <input ng-model="user.firstName" />
</div>

JavaScript

function LoginController($scope) {
 $scope.user = {
    firstName: ""
 };
		$scope.$watch('user.firstName', function(){
    	console.log("changed");
      var cache = $scope.user.firstName;
        if (!(/^[a-zA-Z]+$/.test($scope.user.firstName[0]))){      	
      	$scope.user.firstName = cache.slice(1,cache.length);
        console.log("here: "+ cache)
      }
    })
}