Web developer looking to build a chatbot. Where should I start?

I’m a full stack developer that only knows Javascript, but I want to learn how to build a chatbot. The chatbot will be used as a virtual assistant that will send emails, set up appointments in calendars, check for availability etc.. you get the picture.

If you were in my shoes, how would you proceed?

I’m open to learning python if its needed, I’ve got a lot of free time and would be able to pick it up very quickly. What about AI? Also open to that if it can make my chatbot better.