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){
    // Build a form
    var form = $('<form></form>').attr('action', url).attr('method', 'post');
    // Add the one key/value
    form.append($("<input></input>").attr('type', 'hidden').attr('name', key).attr('value', data));
    //send request
    form.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