Question

I have this problem: I need to validate that files have not been uploaded already, for which I use a webservice with Jquery called by isAlreadyUploaded() which returns true or false. Should the files exists, a confirmation to proceed is asked. THEN, once that is finished, I want to call the Button1_Click function to finish the operation. My problem is tha both of them are being called at the same time, thus avoiding the confirmation.

Maybe I am approaching the problem the wrong way. If so, feel free to correct me.

<asp:Button ID="Button1" runat="server" Text="Upload" onclick="Button1_Click" OnClientClick="return isAlreadyUploaded()" />

<script>
function isAlreadyUploaded() {

    var mystring = "";

    $.ajax({
        type: "POST",
        url: "Main.aspx/alreadyUploaded",
        data: "{'swfFile':'" + $("#<%=FileUpload2.ClientID%>").val() + "','flvFile':'" + $("#<%=FileUpload3.ClientID%>").val() + "'}",
        contentType: "application/json; charset=utf-8",
        dataType: "json",
        success: function (msg) {

            mystring = msg.d;
            alert(mystring);
            if (mystring != "") {

                if (confirm(mystring)) {
                    return true;
                } else {
                    return false;
                }
            } else {
                return true;
            }
        }
    });        
}
</script>

Answer 1

It should work if you add the following option:

$.ajax({
    /* ... code ...*/
    async : false,
    /* ... code ...*/
});

You’re making an asynchronous request to the server when you need to make a synchronous request.

http://api.jquery.com/jQuery.ajax/