File Download requests using jquery/POST request with psuedo ajax

filedownloader.js

// Takes a URL, param name, and data string
// Sends to the server.. The server can respond with binary data to download
jQuery.download = function(url, key, data) {
    $('<form/>')
        .attr('action', url)
        .attr('method', 'post')
        .append($('<input/>')
            .attr('type', 'hidden')
            .attr('name', key)
            .attr('value', data))
        .appendTo('body')
        .submit()
        .remove();
};

sinatra_server.rb

# A Tidbit of sinatra code to respond
# Assume url is a set variable
# Assume 'key' is the key of the value used in the javascript

post url do
  data = params[:key]
  puts request.body.read
  headers['Content-Type'] = "application/octet-stream"

  body(data)
end