what i need is a system that will let me send some data when a user clicks a link.
for example, if i had an html or javascript file that would display a color depending on data it gets, and the link you click to get there sends the data to that site that determines the color (sets a variable in javascript, or something like that).
i havent tried anything yet since i am new to html and have no idea how to do things that involve interacting scripts. i have looked at github projects with the results i want that use a '#' in the url
You can send the color you want the other site to show in a GET parameter.
E.g, your anchor could look something like this:
<a href="site.com/page?color=red">Red</a>
Then, on site.com/page, you can use JavaScript to get the color parameter value:
const color = new URLSearchParams(window.location.search).get('color')