给你个例子你看下吧
<tr>
<td>分段数:</td>
<td colspan="5"><input name="LevelNum" type="text" id="LevelNum" onKeyDown="doEnter();" size="5" >
请录入数字后直接按回车键
<script language="JavaScript" type="text/JavaScript">
function doEnter() {
if (event.keyCode==13){
var i,j;
i=LevelNum.value;
str='<table width="100%"><tr><td><div align="center">层级数</div></td><td colspan="2"><div align="center">字段一</div></td><td><divalign="center">字段2</div></td></tr>';
for ( j=1;j<=i;j++){
str+='<tr><td><div align="center">第';
str+=j;
str+='层</div></td><td><div align="center"><input name="textfield2" type="text" size="5"></div></td><td><divalign="center"><input name="textfield22" type="text" size="5"></div></td><td><div align="center"><input name="textfield222" type="text" size="5">%</div></td></tr>';
}
str+='</table>';
window.LevelTable.innerHTML=str;
}
}
</script></td>
</tr>
<tr>
<td> </td>
<td colspan="5" id="LevelTable"> </td>
</tr>
<tr>
<td>分段数:</td>
<td colspan="5"><input name="LevelNum" type="text" id="LevelNum" onKeyDown="doEnter();" size="5" >
请录入数字后直接按回车键
<script language="JavaScript" type="text/JavaScript">
function doEnter() {
if (event.keyCode==13){
var i,j;
i=LevelNum.value;
str='<table width="100%"><tr><td><div align="center">层级数</div></td><td colspan="2"><div align="center">字段一</div></td><td><divalign="center">字段2</div></td></tr>';
for ( j=1;j<=i;j++){
str+='<tr><td><div align="center">第';
str+=j;
str+='层</div></td><td><div align="center"><input name="textfield2" type="text" size="5"></div></td><td><divalign="center"><input name="textfield22" type="text" size="5"></div></td><td><div align="center"><input name="textfield222" type="text" size="5">%</div></td></tr>';
}
str+='</table>';
window.LevelTable.innerHTML=str;
}
}
</script></td>
</tr>
<tr>
<td> </td>
<td colspan="5" id="LevelTable"> </td>
</tr>
给每个input加上一个id属性,id的值含一个自增的数字如id=j
然后用getElementById()
<tr>
<td><input type=text value="333"></td>
<td>asdfasfd</td>
<td>1111111</td>
</tr>
</table><script language="JavaScript">
<!--//取table
var elTable = document.getElementById( "tb" );
//复制最后一行
var elNewRow = elTable.rows[ elTable.rows.length-1 ].cloneNode(true);
//把新行的所有input中的内容清空
var rgelInput = elNewRow.getElementsByTagName("input");
for ( var i=0; i<rgelInput.length; i++ ) rgelInput[i].value = "";
//贴到表格最后
elTable.rows[elTable.rows.length-1].parentNode.appendChild( elNewRow );
//取下面所有input
//法1.直接用 rgelInput 咯
//...
//法2.从td取,三种方式
elNewRow.cells[0].getElementsByTagName("input")[0].value = "fdfd"
elNewRow.cells[0].firstChild.value = "343443";
elNewRow.cells[0].childNodes[0].value = ",m,./.,m."//-->
</script>