How to validate file size before upload at client side ( Javascript ) ?

[fac]

Hi all,

I'm using control "FileUploadField" to upload file to the server. The file to be upload is required to not exceed maximum size.

Therefore, I wonder how can I check the size of the file before uploading , by Javascript ?

Thanks for help.

My code :

+ FileUploadField :

 <ext:FileUploadField ID="FileUploadFieldAttachment" runat="server" Width="212" />

+ Button Action :

   <ext:Button ID="ButtonUpload" runat="server" Text="Upload">
                                        <Listeners>
                                            <Click Fn="ValidateFileSize"></Click>
                                        </Listeners>
                                        <DirectEvents>
                                            <Click OnEvent="InsertNewAttachment">
                                            </Click>
                                        </DirectEvents>
                                    </ext:Button>

I have used this function, but it does not work :

 function ValidateFileSize() {
            var node = document.getElementById('ChildPage_FileUploadFieldAttachment-file');
            alert(node);
            if (node != null) {
                alert(node.files);
                if (node.files != null) {
                    var check = node.files[0];
                    alert(check);
                    if (check != null) {
                        var checkSize = check.fileSize;
                        alert(checkSize);
                        if (checkSize / 1024 > 10240) {
                            Ext.Msg.alert('Confirm', "Your file is too big !");
                            return false;
                        }
                    }
                }
            }
            return true;
        }

[Daniil]

Hi,

The browser security policy to don't allow JavaScript full free to work with local files, therefore I'm not sure there is a good cross-browser solution.

I would look it on the internet. For example:
http://www.kavoir.com/2009/01/check-...uploading.html

[fac]

Thanks for your help. I configed web.config with MaxRequestLength attribute in HttpRuntime tag.