title: Tell if android app is installed using javascript or jquery
body: <p>I have an android app that can be accessed through a web browser too. I need to put a banner to let the user install the android application. How can i tell (if the user enters to the application through the web browser) using javascript or jquery, if the android app is already installed on his mobile phone?
  All i want to do is: If the user clics the banner and the app is already installed, open the android app. Otherwise, redirect the user to the playstore to let him install the app.</p>