Authorization Code and Credentials Flow for Private Clients

I have created a sample javascript app with functionality of Authorization Code and Credentials Flow for Private Clients. 

Just visit Blogshot: https://www.catchontosalesforce.com/p/authorization-code-and-credentials-flow.html 

Github : https://github.com/Priyananth-Salesforce/Headless-SF-Authenication--Login-Via-Javascript-App