<!DOCTYPE html>
<html>
<script src="http://ajax.googleapis.com/ajax/libs/angularjs/1.4.8/angular.min.js"></script>
<body ng-app="">
<input ng-keydown="count = count + 1" ng-init="count=0" />
<h1>{{count}}</h1>
<p>This example will increase the value of the variable "count" every time a key is pressed in the input field.</p>
</body>
</html>