Ng-Keydown-7

For true value of keyDown variable ng-class keyDown will apply.

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <title>Welcome to LearnKode - A code learning platform</title>
    <script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.4.2/angular.min.js"></script>
<style>
    .keyDown {
        background-color: red;
    }
</style>
</head>
<body ng-app>
    <div>
        Text: <input type="text" ng-model="text" ng-class="{true:'keyDown'}[keyDown]" ng-keydown="keyDown=true" /><br />
    </div>
</body>
</html>

Output