Static website with user tunable parameters [closed]

  html, javascript, node.js

I have a static website that is already fully functional and includes an animation. I am trying to add an admin page in which a user could change parameters of the animation and save them so that any future users will have the new parameters. I am storing these parameters in a JSON file. What is the simplest way of implementing this ? I started implementing a backend using Node.JS to handle post requests but it seems to require significant changes to the rest of the website.

Sorry if this is a bit confused, I am quite new to web development.

Source: Ask Javascript Questions