无法用Node返回.json数据。js(歌珥错误)

I'm starting learning node.js, but I have a little problem. I have an ajax function that call a server listening on port 8001. Afer I open and load a .json file and I want to send back to the page. For what concern the loading, there is no problem, but when I send back to the page, I get this error : on Chrome "POST http: //localhost:8001/ net::ERR_CONNECTION_REFUSED"; on Firefox "...Reason : CORS request failed."I'm starting learning node.js, but I have a lit