Question

I wonder if it’s possible to show a warning or open a pop-up, which would say update your IE to latest version or use Firefox / Chrome / Safari instead, when browser is Internet Explorer IE8 or older…

I guess I should use that code below inside the tags…

<!--[if lt IE 9]>
...i should use code here...
<![endif]-->

Is it smart to deceted browser with jQuery and loading jQuery lib? Or is it better to just use regular javascript in order to avoid additional issues with very old browsers?

Answer 1

You have two options:

1. Parse the the User-Agent String

   // Returns the version of Internet Explorer or a -1
   // (indicating the use of another browser).
   function getInternetExplorerVersion() {
       var rv = -1; // Return value assumes failure.
   
       if (navigator.appName == 'Microsoft Internet Explorer') {
           var ua = navigator.userAgent;
           var re  = new RegExp("MSIE ([0-9]{1,}[\.0-9]{0,})");
   
           if (re.exec(ua) != null) {
               rv = parseFloat( RegExp.$1 );
           }
       }
   
       return rv;
   }
   
   function checkVersion() {
       var msg = "You're not using Internet Explorer.";
       var ver = getInternetExplorerVersion();
   
       if ( ver > -1 ) {
           if ( ver >= 9.0 ) {
               msg = "You're using a recent copy of Internet Explorer."
           }
           else {
               msg = "You should upgrade your copy of Internet Explorer.";
           }
       }
       alert(msg);
   }
   

2. Using Conditional Comments:

   <!--[if gte IE 9]>
   <p>You're using a recent version of Internet Explorer.</p>
   <![endif]-->
   
   <!--[if lt IE 8]>
   <p>Hm. You should upgrade your copy of Internet Explorer.</p>
   <![endif]-->
   
   <![if !IE]>
   <p>You're not using Internet Explorer.</p>
   <![endif]>
   

Reference: Detecting Windows Internet Explorer More Effectively