This is my favorite new feature in HTML. It allows us to define custom HTML elements as classes and talk to them using attributes.
https://gist.github.com/lindseyjohnasterius/96e696d780b74a2d800163760bc6293d
Here is my Gist explaining how I do it, but the javascript.info article is newer and better
https://gist.github.com/lindseyjohnasterius/96e696d780b74a2d800163760bc6293d
Here is my Gist explaining how I do it, but the javascript.info article is newer and better