In my project, I need to make a public site with many forms. These forms will read and write some strings into a private Google Sheets document. How should I handle this public-to-private while allowing input/read? When I search for something about this, I only found tutorials using Node Js or Python, but I want to do this on my site (client-side).
I found something in the tutorial below, when I create a KeyFile and an e-mail on Sheets API credentials, but the tutorial use Node Js. How to make this tutorial using just JavaScript?