<script>
function add()
{
var t=document.getElementsByTagName('table')[0];for(var i=0;i<t.rows.length;i++)
{
var td=document.createElement('td');
td.innerText='new text';
t.rows[i].insertBefore(td);
}
}
</script>
<body>
<table>
<tr>
<td>1</td>
<td>2</td>
<td>3</td>
<td>4</td>
</tr>
<tr>
<td>A</td>
<td>A</td>
<td>A</td>
<td>A</td>
</tr>
</table>
<input type=button value='添加列' onclick='add()'>
</body>
<script>
i=0;
j=0;
function addcol()
{
var obj=document.getElementById('tbl')
if(i%4==0){j++;obj.insertRow()}
tmptd=obj.rows[j].insertCell();
tmptd.innerHTML=i++;
tmptd.style.border='1px';
tmptd.style.borderColor='black';
tmptd.style.borderStyle='solid';
}
</script>
</HEAD><BODY>
<table id="tbl">
<tr></tr>
</table>
<button onclick="addcol()">增加一列</button>
</BODY>