<html>
<head>
<script language="javascript">
function add()
{
document.getElementById("f1").innerHTML+="<input type='text'>";
}
function del()
{
document.getElementById("f1").innerHTML-="<input type='text'>";
}
</script>
</head>
<body>
<form id="f1">
<input type="button" value="Add" onclick="add()">
<input type="button" value="Delete" onclick="del()">
</form>
</body>
<html>