Focus traps are great and a crucial part of making a site with modals accessible, and I also think reimplementing things from scratch can be a great way to lear

Focus traps are great and a crucial part of making a site with modals accessible, and I also think reimplementing things from scratch can be a great way to learn about them. However I'd caution anyone against using accessibility scripts written from scratch. Accessibility is notoriously hard to get right and there's numerous nontrivial details that need to be nailed down. > The code is pretty W3’s example, just a bit simplified and explained. The problem here being that W3's solution is cross-browser compatible and you can reasonably expect it to work on screen readers of all sorts. The code in the post won't even work correctly on all modern browsers. I wouldn't be saying all this otherwise, as again, rewriting things is great for learning them. However the title of the post, "The only trap focus function you need for your modals", can mislead your readers into a false sense of security.