How to determine browser capabilities

Web browsers sometimes differ in the way they render a page. For this reason you may wish to find out which particular browser a visitor is using in order to use some browser-specific CSS.

The following JavaScript defines a simple browser detection object that determines the browser's name and version by decoding the navigator.userAgent string.

function browserDetect()
{
  var browserNames=new Array("Opera", "MSIE","Netscape","Firefox");
  this.name="NK";
  this.mainVersion="NK";
  this.minorVersion="NK";
  
  for (var i=0; i< browserNames.length; i++)
  {
   var pattern='('+browserNames[i]+')'+'.([0-9]+)\.([0-9]+)';    
   var myRegExp=new RegExp(pattern);
   if (myRegExp.test(navigator.userAgent))
    {
      var results=myRegExp.exec(navigator.userAgent);
      this.name=results[1];
      this.mainVersion=results[2];
      this.minorVersion=results[3];
      break;
    }
  }
}

To use this in a script, you create an instance of this object:

var browser = new browserDetect();

The property browser.name will then give you the name of the browser (MSIE, Opera, Netscape or Firefox), browser.mainVersion will show the main version number and browser.minorVersion contains the minor version number.

This is not foolproof. It is much better to avoid writing browser-specific code.