How do I send external parameters with custom-login

[ShengJie Bian]

I want accessspotfire pageby using custom-login(https://community.spotfire.com/wiki/create-custom-login-page-tibco-spotfirer).

I know how to login with params in the url;but how to send other optional paramters with this api(I noticed that the last paramter of 'login' method might be able to do this but I do not know how.)And how to read these params in spotfire(example:http://localhost:90/spotfire/resources/custom-login/custom-login-app-exa...)

Could someone give me an example I am a Noob at JS/Auth