browser crash on page reload or redirect (use continues 3 ajax request at every 3 second)

browser start crashing on page reload or redirect to another page after spending more than 10 minute on same webpage.

$(document).on('click','.logout', function()
{
 if(vaani_UserOnCall=='false')
 {
    loadershow();
    vaani_source.close();
    window.onbeforeunload = null;
    $(window).unbind('beforeunload');   
    
    vaani_login = false;
    window.location.href='../logout.php';
  }
}