자바스크립트 질문입니다

<p id="adRow"> 		  <input type="button" value="추가" onClick="addRow('dataTable')" class="button"/> 		  <input type="button" value="삭제" onClick="deleteRow('dataTable')" class="button"/> 		</p>									<table id="dataTable" class="dataTable" border="1">			<tbody>			<tr><p>				<td>					<input type="checkbox" name="chk[]" checked="checked" />				</td>				<td>					<div>					<label>과일</label>					<select name="sub1[]" required>						<option value="">선택하세요</option>						<option value="1">사과</option>						<option value="2">수박</option>					</select>					</div>				</td>				<td>					<label>과정</label>					<select name="sub5[]" required>						<option value="">선택하세요</option>						<option value="표준">표준과정</option>						<option value="응용">응용과정</option>					</select>				</td>					</p></tr>		 </tbody>		</table>  <script>function addRow(tableID) {	var table = document.getElementById(tableID);	var rowCount = table.rows.length; 		var row = table.insertRow(rowCount);		var colCount = table.rows[0].cells.length;		for(var i=0; i <colCount; i++) {			var newcell = row.insertCell(i);			newcell.innerHTML = table.rows[0].cells[i].innerHTML;		}} function deleteRow(tableID) {	var table = document.getElementById(tableID);	var rowCount = table.rows.length;	for(var i=0; i<rowCount; i++) {		var row = table.rows[i];		var chkbox = row.cells[0].childNodes[0];		if(null != chkbox && true == chkbox.checked) {			if(rowCount <= 1) {               // limit the user from removing all the fields				alert("Cannot Remove all the Passenger.");				break;			}			table.deleteRow(i);			rowCount--;			i--;		}	}}</script>