Send file via HTML5 to Web server

// client side

let getFiles () : FileList =
    let input = JS.Document.GetElementById("uploadInput") |> As<HTMLInputElement>
    input?files

let sendFiles (el:Dom.Element) (ev:Dom.Event) =
    ev.PreventDefault()
    JS.Document.GetElementById("response").InnerHTML <- ""
    let oReq : XMLHttpRequest = JS.Inline("new XMLHttpRequest()") // WORKAROUND 1
    let url = "/upload"
    oReq.Open("POST",url, true)
    oReq.Onload <- fun ev -> 
        Console.Log("Uploaded", ev)
    oReq.Onerror <- fun ev -> 
        Console.Log("Error", ev)
    oReq.Onreadystatechange <- fun ev ->
        let response = oReq.StatusText + ": " + oReq.ResponseText
                                      + " ReadyState: " + oReq.ReadyState.ToString()
        Console.Log(response)
        if  (oReq.ReadyState = 4) then
             JS.Document.GetElementById("response").InnerHTML <- response
    let files = getFiles ()
    JS.Inline("$0.send($1)", oReq, files.[0]) // WORKAROUND 2

// server side

let StreamingUploadFilePage (ctx:Context<EndPoint>) =
    try
        let stream = ctx.Request.Body
        if (stream.Length > (int64 0) && stream.Length < (int64 2.5E6)) then
                let count = int stream.Length
                let buffer = Array.zeroCreate<byte> count
                let res = stream.Read(buffer, 0, count)
                use fs = File.Open(destinationPath, FileMode.Create)
                fs.Write(buffer, 0, count)
                Content.Text ("Uploaded! (" + res.ToString() + ")")  
        else 
            Content.Text ("File Size is not permitted: " + stream.Length.ToString())
            |> Content.SetStatus (Http.Status.Custom 400 (Some "Bad Request"))  
    with
    |exc ->  
        Content.Text exc.Message
        |> Content.SetStatus Http.Status.InternalServerError