<script language=javascript >
function Check(_input)
{
if(window.Form1.input1.value.length>5)
{
alert("ffdfdf");
}
}
</script>
</HEAD>
<body MS_POSITIONING="GridLayout">
<form id="Form1" method="post" runat="server">
<input id="input1" type="text" onblur="Check(this);">
</form>
</body>