Is this possible to get authorisation code by JavaScript for Box API

I am using third party tool which will interact with Box enterprise account and there is no configuration are available to configure redirect URL.
For this, first time when my app will try to access account it will be redirected to Box page. Box finally redirects user to my redirected URL after accepting user credentials. This redirected URL will have a authorisation code.

Is this possible to get authorisation code by JavaScript for Box API?
Below is how i am trying to authorising:
And below how i will get code:

You ill need to look at TIB (Tyk Identity Broker) if you want to authorize againt a third-party OAuth token provider. Currently tyk is an OAuth server in it’s own right, it doesn;t pass through OAuth at the moment, not without the identity broker (which can handlethe OAuth 3-legged flow, and then exchange the box token for a tyk token so that requests can pass through the gateway).

However, AFAICR TIB does not currently have a connector for Box, but it should be trivial to add if you extend the goth lib.

Actually, I need the JavaScript code so that i can customise that code to generate authorisation code for BOX API. I am using 3rd part tool and there were no configuration are available to redirect URL. thats why i am looking JavaScript code to get that code by redirect URL.