求助!!!!判断file类型输入框是否为空<form name="form3" ENCTYPE="multipart/form-data" ACTION="upimage.asp" METHOD="POST" target="_blank" ><table width="516" height="124" border="0" align="center">
<tr>
<td height="47"><span class="STYLE11">选择您上传的照片：</span></td>
</tr>
<tr>
<td height="30"><input NAME="picture" TYPE="FILE"></td>
</tr>
<tr>
<td><div align="center">
<input type="submit" value="提交" name="B1" >
</div></td>
</tr>
</table></form>
<tr>
<td height="47"><span class="STYLE11">选择您上传的照片：</span></td>
</tr>
<tr>
<td height="30"><input NAME="picture" TYPE="FILE"></td>
</tr>
<tr>
<td><div align="center">
<input type="submit" value="提交" name="B1" >
</div></td>
</tr>
</table></form>
<html>
<head>
<SCRIPT>
function check()
{
if (document.form3.picture.value == "")
{
alert("附件为空");
return false;
}
return true;
}
</SCRIPT>
</head>
<body onload="">
<form name="form3" ENCTYPE="multipart/form-data" ACTION="upimage.asp" METHOD="POST" target="_blank" onsubmit="return check()">
<table width="516" height="124" border="0" align="center">
<tr>
<td height="47"><span class="STYLE11">选择您上传的照片：</span></td>
</tr>
<tr>
<td height="30"><input NAME="picture" TYPE="FILE"></td>
</tr>
<tr>
<td><div align="center">
<input type="submit" value="提交" name="B1">
</div></td>
</tr>
</table></form>
</body>
</html>