JavaScript Close App Phonegap

<!DOCTYPE HTML>
<html>
  <head>
    <title>PhoneGap</title>

        <script type="text/javascript" charset="utf-8" src="cordova-1.5.0.js"></script>      
        <script type="text/javascript" charset="utf-8">

            function onLoad()
            {
                  document.addEventListener("deviceready", onDeviceReady, true);
            }

            function exitFromApp()
             {
                navigator.app.exitApp();
             }

        </script>

    </head>

    <body onload="onLoad();">
       <button name="buttonClick" onclick="exitFromApp()">Click Me!</button>
    </body>
</html>
Homely Heron