how to limit the additions field?

Hi,
If someone here is willing to help me I would really appreciate

how to limit the addition of columns in the following html code, let say only up to 5 only?

<script type="text/javascript"><!--
function addFriend() {
	var tbl = document.getElementById('my_friends');
	var iteration = tbl.tBodies[0].rows.length;
	newRow = tbl.tBodies[0].insertRow(-1);
	var newCell = newRow.insertCell(0);
	newCell.innerHTML = '<?php echo $entry_friend; ?>';
	var newCell1 = newRow.insertCell(1);
	var el = document.createElement('input');
	el.type = 'text';
	el.name = 'friends[]';
	el.size = 30;
	el.maxlength = 45;
	newCell1.appendChild(el);
//	if (newCell > 2) tbl.addCell(newCell + 1);
}

function removeFriend() {
	var tbl = document.getElementById('my_friends');
	var lastRow = tbl.rows.length;
	if (lastRow > 2) tbl.deleteRow(lastRow - 1);
}
//--></script>

Code (markup):

Thanks in advance