Question

I need to block IE versions upto 6. for user agent strings I wrote a regex which blocks IE 4 5 and 6. But I came across this string:

Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0; TheFreeDictionary.com; FunWebProducts; FBSMTWB; GTB6; Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1) ; InfoPath.2)

In this string, there is MISE 6.0 mentioned so my regex blocks it. However it is actually IE 8 browser. So how can I construct a regex that scans for IE which is above 6 and if IE 4-5-6 appears again in the string it will ignore it.

Answer 1

Do not look for occurrences of MSIE 6.0 to block, detect the version as a floating point number with code like this: (You didn’t specify a language so I give the example in PHP)

preg_match( '/MSIE ([0-9]{1,}[\.0-9]{0,})/', $userAgent, $matches );
$version = float( $matches[1] );
if( $version <= 6.0 ) {
    // BLOCK
}

The code above will use the first occurrence of MSIE x.x to detect the version and will ignore the rest.

UPDATE:

In Javascript:

var re = new RegExp('/MSIE ([0-9]{1,}[.0-9]{0,})/g');
if(re.exec(userString) != null) {
   version = parseFloat(RegExp.$1);
}