Dear chrisluo,
Please refer to the following snippet:
<script type="text/javascript">
function CuteWebUI_AjaxUploader_OnQueueUI(list) {
var mycancelall = document.getElementById("mycancelall"); if (list.length < 2) {
mycancelall.style.display = "none"; return;
}
mycancelall.style.display = "";
}
function DoCancelAll() {
var uploader = document.getElementById('<%=UploadAttachments1.ClientID %>');
uploader.cancelall();
}
</script>
</head>
<body>
<form id="form1" runat="server">
<div>
<CuteWebUI:UploadAttachments runat="server" ID="UploadAttachments1" />
<hr />
<asp:Button runat="server" ID="BtnSubmit" Text="MySubmit" />
<button id="mycancelall" onclick="DoCancelAll();return false;" style="display: none">
Cancel All Uploads</button>
</div>
</form>
</body>
</html>
Thank you for asking