用jQuery在代码后面调用ASP.NET FileUpload函数

Question

I'm using the ASP.NET FileUpload control.

To upload a file, a user must:

1. Browse to select a file from his/her device,
2. Click the upload button to upload the file to the server.

Is it possible to skip step 2 (the Upload button) and call the 'uploadFile_Click' function on the server through a jquery (postback) once a file is selected? I'm trying the following method but I need some help to finalize it.

ASPX PAGE

<asp:FileUpload runat="server" ID="UploadImages" />
<asp:CustomValidator ID="CustomValidator1" runat="server" ControlToValidate="UploadImages" ClientValidationFunction="ValidateUpload" />

CODE BEHIND

protected void uploadFile_Click(object sender, EventArgs e)
{
// Upload code
}

JQUERY

function ValidateUpload() {
var FileUpload_function = document.getElementById('UploadImages');

        if (FileUpload_function.value == '') {
            return false;
        }
        else {

           ** Here I want to trigger a postback to call the uploadFile_Click. Is that possible? **
        }
        return true;

    }

Answer 1

Some (most?) browsers will not allow you to call the click event on an input HTML element if it is of type file (ie. an asp:fileupload control). It is considered a security risk.