<script language="JavaScript">
function A()
{
var oas = new ActiveXObject("Scripting.FileSystemObject");
var d = document.a.b.value;
var e = oas.getFile(d);
var f = e.size;
alert(f + " bytes");
}
</script>
</head>
<body>
<form name="a">
<input type="file" name="b">
<input type="button" name="c" value="SIZE" onClick="A();">
</form>