js判断文档上传

<script type="text/javascript">
//判断上传文件大小
var isIE = /msie/i.test(navigator.userAgent) && !window.opera;
function fileChange(target) {
var fileSize = 0;
if (isIE && !target.files) {
var filePath = target.value;
var fileSystem = new ActiveXObject("Scripting.FileSystemObject");
var file = fileSystem.GetFile(filePath);
fileSize = file.Size;
} else {
fileSize = target.files[0].size;
}

var size = fileSize / 1024;
if (size > 60000) {
if (navigator.userAgent.indexOf("MSIE") > 0)
$("#FileUpload").val("");

$.messager.alert("提示", "附件不能大于60M");
var a = document.getElementsByName("FileUpload");
a[0].value = "";
}
}
</script>