title: Detect if Android app has been installed on the device using a mobile web page - PHP and JS
body: <p>I have a requirement like this and something similar to that has been implemented by Android Pit app-store.</p>
  
  <p>I need to check if the Android app has been installed on the device using a mobile web page (PHP and JS), and if installed launch the app immediately.</p>
  
  <p>These are the intermediate pages used by Android pit. </p>
  
  <p><strong>When app has not been installed</strong> - <a href="http://www.androidpit.com/en/android/market/app-center-mobile?pname=com.ocito.laredoute" rel="nofollow noreferrer">http://www.androidpit.com/en/android/market/app-center-mobile?pname=com.ocito.laredoute</a></p>
  
  <p><strong>When app has been already installed</strong> - <a href="http://www.androidpit.com/en/qrdl/com.mobage.ww.a692.Bahamut_Android" rel="nofollow noreferrer">http://www.androidpit.com/en/qrdl/com.mobage.ww.a692.Bahamut_Android</a></p>
  
  <p>Does anyone know how to implement this?</p>