codice:
<HTML>
<HEAD>
<META NAME="GENERATOR" Content="Microsoft Visual Studio 6.0">
<TITLE></TITLE>
<SCRIPT ID=clientEventHandlersJS LANGUAGE=javascript>
<!--
function button1_onclick() {
	var ntb = document.getElementById("text1").value;
	if(!isNum(ntb))
	{
		alert("devi inserire un valore numerico");
	}
	else
	{
		var frm = document.getElementById("form1");
		frm.innerHTML = "";
		for(var i = 0; i < parseInt(ntb); i++)
		{
			addTextBox(frm, "text_" + i, "");
			addLine(frm);	
		}
		addSubmit(frm, "submit1", "Submit")
	}
}


function isNum(arg) 
{
	return !isNaN(parseFloat(arg));
}

function addTextBox(form, key, value)
{
	var input = document.createElement("input");
	input.type = "text";
	input.name = key;
	input.value = value;
	form.appendChild(input);
}

function addLine(form)
{
	var input = document.createElement("hr");
	form.appendChild(input);
}

function addSubmit(form, key, value)
{
	var input = document.createElement("input");
	input.type = "submit";
	input.name = key;
	input.value = value;
	form.appendChild(input);
}

//-->
</SCRIPT>
</HEAD>
<BODY>
scegli quanti TextBox vuoi: <INPUT type="text" id=text1 name=text1>
<INPUT type="button" value="Button" id=button1 name=button1 LANGUAGE=javascript onclick="return button1_onclick()">
<HR>

<form id="form1" name="form1"  action=? method=get>
</form>

</BODY>
</HTML>