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 line added to print id -rows => '2', -columns => '6', -defaults => [ '2 Fastest' ], -onClick=>"checkBoxClick()", #modified as advised by ikegami, but still not functioning ), p, }