[SOLVE] How can i acess Calendar instances by id?

Hello everyone, I am learning by myself to make web app and now i am I am having difficulty in one issue that need your help to solve, pls.
This is my live code: https://jsfiddle.net/5g7pw9rL/
My question is how can I acess to calendar instance by its “id” and change it’s value?
Thank you so much.

You can’t access it, you need to save calendar instance in some array or object, like here https://jsfiddle.net/ygj25spc/

Thank you so much. You make my day.