附件的JavaScript客户端验证

Question

请帮助我解决这个问题我不知道为什么当我附加.pdf它有问题，当我附加图像时它可以附加文件唯一发生的事情就是当我附加.pdf它是不附加。提前谢谢。

    //Trim the input text
    function Trim(input) {
        var lre = /^\s*/;
        var rre = /\s*$/;
        input = input.replace(lre, "");
        input = input.replace(rre, "");
        return input;
    }

    // filter the files before Uploading for text file only  
    function CheckForTestFile() {
        var file = document.getElementById('<%=fudata.ClientID%>');
        var fileName = file.value;
        //Checking for file browsed or not 
        if (Trim(fileName) == '') {
            alert("Please select a file to upload!!!");
            file.focus();
            return false;
        }

        //Setting the extension array for diff. type of text files 
        //var extArray = new Array("doc", "docx", "pdf", "jpg", "png");
        var extArray = new Array("png", "jpg", "pdf");

        var Extension = fileName.substring(fileName.lastIndexOf('.') + 1).toLowerCase();

        //matching extension with our given extensions.
        for (var i = 0; i < extArray.length; i++) {
            if (extArray[i] == Extension) {
                return true;
            }
        }
        alert("Please only upload files that end in types:  "
         + (extArray.join("")) + "\nPlease select a new "
         + "file to upload and submit again.");
        file.focus();
        return false;
    }

HTML

<asp:Panel ID="PanelAttacheFile" runat="server" EnableTheming="True">
    <asp:DataList ID="DataList1" runat="server" DataKeyField="tafID" RepeatColumns="5">
        <ItemTemplate>
            <asp:ImageButton ID="ImageButton1" ImageUrl='<%# "~/TicketAttachmentImage.ashx?AsThumbnail=true&imageid=" & CStr(Eval("tafID"))%>'
                                    runat="server" />
            <br />
            <asp:Label ID="FileNameLabel" runat="server" Text='<%# Eval("FileName") %>' />
            <br />
            <asp:LinkButton ID="LinkButton1" runat="server"  CommandName="remove">Remove</asp:LinkButton>
            <br />
            <asp:HyperLink ID="downloadimg" runat="server" Text="View" NavigateUrl='<%#"~/TicketAttachmentImage.ashx?AsThumbnail=false&imageid=" & CStr(Eval("tafID")) & "&filename=" & Eval("FileName")%>'
                                    Target="_blank" />
        </ItemTemplate>
    </asp:DataList>
</asp:Panel>

<table style="width: 100%">
    <tr>
        <td class="captionwidth "></td>
        <td class="captionwidth ">
            <asp:Button ID="bttnPost" runat="server" Text="Post" ValidationGroup="group1" Width="87px" CssClass="ButtonStyle" />
        </td>
        <td class="fileupwidth">
            <asp:FileUpload ID="fuData" runat="server" Width="328px" />
        </td>
        <td>
            <asp:Button ID="bttnAttached" runat="server" Text="Attach" Width="76px" OnClientClick="return CheckForTestFile();" CssClass="ButtonStyle" />
        </td>
    </tr>
</table>