show alert before close the window by javascript

window.onbeforeunload = function (evt) { 
  var showmessage = 'Are you sure you want to leave?'; 
  if (typeof evt == 'undefined') { 
    evt = window.event; 
  } 
  if (evt) { 
    evt.returnValue = showmessage; 
  } 
  return showmessage ; 
}  

Detect the browser by Javascript

by this javascript function we can detect browser .



function BrowserType()
   {
       var brwser;
       var valNavigator = navigator.userAgent.toLowerCase();
       if(valNavigator.indexOf("firefox") > -1)
       {
          brwser="Firefox";
       }
       else if(valNavigator.indexOf("opera") > -1)
       {
          brwser="Opera";
       }
       else if(valNavigator.indexOf("msie") > -1)
       {
          brwser="IE";
       }
       else if(valNavigator.indexOf("safari") > -1)
       {
          brwser="Safari";
      }
}