In my website, I'm trying to design a calendar that displays when dates are marked Not Available" in my calculator. The way I aim to do this is by writing a function "IsAvailable" that takes in the date and returns true if it lacks the "Not Available" event, and false if it has it. I have been trying to use the google API, but I'm having a very hard time finding resources online.

I've tried to follow tutorials, but most of them don't work since I'm using NextJS/Typescript. I kept getting an error when I tried defining "var gapi = window.gapi." All help is appreciated.