<form action="#">
<p>
<input type="button" value="先頭に1行挿入" onclick="fTalbeInsertRowFirst()">
<input type="button" value="先頭から1行削除" onclick="fTalbeDeleteRowFirst()">
</p>
</form>
<div class="tbl">
<table id="tableK">
<tr><th>item3</th><td>3-1</td><td>3-2</td><td>3-3</td></tr>
<tr><th>item2</th><td>2-1</td><td>2-2</td><td>2-3</td></tr>
<tr><th>item1</th><td>1-1</td><td>1-2</td><td>1-3</td></tr>
</table>
</div>
<script>
function fTalbeDeleteRowFirst(){
var tObj=document.getElementById("tableK");
var idx=tObj.rows["length"];
if(idx<1) return false;
/* 1行挿入(先頭行から削除)*/
tObj.deleteRow(0);
}
function fTalbeInsertRowFirst(){
var tObj=document.getElementById("tableK");
/* 行番号 */
var idx=0;
/* 行数 */
var idy=tObj.rows["length"]+1;
/* 1行挿入(先頭行に挿入)*/
var insObj=tObj.insertRow(idx);
//var n=insObj.insertCell(0);
var n=document.createElement("th"); insObj.appendChild(n);
var x=insObj.insertCell(1);
var y=insObj.insertCell(2);
var z=insObj.insertCell(3);
n.innerHTML="item"+idy;
x.innerHTML=idy+"-1";
y.innerHTML=idy+"-2";
z.innerHTML=idy+"-3";
}
</script>