unity - WWW request does not connect using webgl platform

I use request like code below:

string url = "http://localhost:51820/Home/login/" + end+"/";
        WWW www2 = new WWW(url);

        StartCoroutine(waitForLogin(www2));

It works fine in the editor but the html build shows a connection problem. message of www error is only "unknown error"

Answer

When you look into your browsers error console, you will likely notice an error message like this:

Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at http://localhost:51820/Home/login/

For security reasons, web browsers do not allow javascript applications to send http requests to localhost when they aren't also loaded via localhost. Note that loading a html document via the file:/// pseudo-protocol is not considered the same as loading from http://localhost.

What you can do as a workaround is put the game into the document directory of your local webserver and also load it via an URL like http://localhost:51820/yourgame/index.html.