form>
<div id=ad></div>
</form>
<input type="button" value="添加" onclick="ad.insertAdjacentHTML('beforeEnd','文本:<input type=text><br/>')">
<div id=ad></div>
</form>
<input type="button" value="添加" onclick="ad.insertAdjacentHTML('beforeEnd','文本:<input type=text><br/>')">
<div id=buttondiv></div>
</form>
<script language="javascript">
i=0
function addbutton()
{
buttondiv.insertAdjacentHTML("beforeEnd","<input type=text name='txt"+i+"'><br>")
}
</script>
<input type="button" value="添加" onclick="addbutton()">
<input type="button" value="添加" onclick="ad.insertAdjacentElement('beforeEnd',document.createElement('input'))">
<div id=ad></div>
</form>