function window.onbeforeprint()
{
document.getElementById('tblmain').style.display ='none';
document.getElementById('tblmain').style.visibility = 'hidden';
}

function window.onafterprint()
{
document.getElementById('tblmain').style.display ='block';
document.getElementById('tblmain').style.visibility = 'visible';
}

<!-- 

//Disable right click script III- By Renigade (renigadeatmediaone.net) 
//For full source code, visit http://www.dynamicdrive.com 

var message=""; 
/////////////////////////////////// 
function clickIE() {if (document.all) {(message);return false;}} 
function clickNS(e) {if 
(document.layers||(document.getElementById&&!document.all)) { 
if (e.which==2||e.which==3) {(message);return false;}}} 
if (document.layers) 
{document.captureEvents(Event.MOUSEDOWN);document.onmousedown=clickNS;} 
else{document.onmouseup=clickNS;document.oncontextmenu=clickIE;} 

document.oncontextmenu=new Function("return false") 
// -->