Can I use $.ajax call for any DocuSign REST API (including OAuth)

There seems to be vert little information about using $.ajax call to a DocuSign REST API on the web.   

1. Is it possible to use $.ajax?
2. If there is, how can use setup $.ajax to
   • perform an OAuth/Auth 
     • Using https://account-d.docusign.com/oauth/auth?response_type=code&scope=signature&client_id=${integrationKey}&redirect_uri=https://localhost
     • Able to do this directly on a web page on the address line but not using $.ajax
   • Get a token from the OAuth/Auth (https://account-d.docusign.com/oauth/token)
   • If a access token is return, use it to GET/POST a DocuSign REST API through $.ajax
3. By passing the CORS policy (Access-Control-Allow-Origin) (tried using the header and body in the $.ajax code to set this up).  This is my big issue.

At this point, I’m at wits end…need help