javascript doesn't work through browsersync

[chriz74x]

I have a situation where my script works perfectly fine when running from project.dev/ while nothing happens when the site is served through localhost:3000/ and the console logs this error:

XMLHttpRequest cannot load http://project.dev/route. No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://localhost:3000' is therefore not allowed access. The response had HTTP status code 500.

The event is attached to a dynamic form (there are many in the same page): $("body").on("submit", ".dynamic-form", function (e){});