<SCRIPT LANGUAGE="JavaScript">
function testFile(x)
{
if(x.value.substr(x.value.lastIndexOf(".")).toUpperCase()!='.JPG')
{
alert("只允许选择JPG文件，你选择的文件格式是："+x.value.substr(x.value.lastIndexOf(".")).toUpperCase());
form1.reset();
}
}
</SCRIPT>
<form method="POST" enctype="multipart/form-data" action="--WEBBOT-SELF--" name="form1">
<p><input type="file" name="F1" size="20" onchange="testFile(this);"><input type="submit" value="提交" name="B1"><input type="reset" value="重置" name="B2"></p>
</form>