Admit it. There are so many times you wish that the localhost-ed version of the application that you are developing in BacboneJS just works. But it doesn’t. And there is only one reason why it doesn’t work.

Cross Origin Resource Sharing

Yeah, the big culprit is CORS. And here is how you circumvent it. This snippet assumes you are using Sinatra for deploying your Rails API.

The Solution

options '/*' do
  response["Access-Control-Allow-Headers"] = "origin, x-requested-with, content-type"
end

This snippet will add a header to the response that will allow cross-origin javascript coming specifically from localhost to be able to call the server and get a response.