The function call document.getElementById('2 Fastest'); returns null, since you are NOT printing any IDs for check boxes. To print Ids, you can use the 'attributes' option of 'checkbox_group' in CGI. The code with ids will look like :

sub generate_form {

    print start_multipart_form(),
        #strong('Your email: '),
        #textfield( -name => 'user_email' ), br, br


        strong('Basic Programs To Choose: '), br
        checkbox_group(
        -name   => 'progname',
        -values => [
            '2 Fastest',
            'MEME',
            'MITRA',
            'SPACE',
            ],
        -attributes=>{'2 Fastest'=>{'id'=>'2 Fastest'}}, #the extra li
+ne added to print id
        -rows => '2',
        -columns => '6',
        -defaults => [ '2 Fastest' ],
        -onClick=>"checkBoxClick()",  #modified as advised by ikegami,
+ but still not functioning
        ),
        p,
}
[download]

Hope this will help.

Cheers !

--VC

---

There are three sides to any argument.....
your side, my side and the right side.