<html xmlns="http://www.w3.org/1999/xhtml"> <head> <script> function boom() { document.getElementById("c").setAttribute('span', 2); document.getElementById("cg").setAttribute('span', 2); } </script> </head> <body onload="boom();"> <table><colgroup id="cg"><col span="3" id="c" /></colgroup></table> </body> </html>