A good introduction to writing a custom hook. The result is useful as well.
https://nick.scialli.me/writing-a-custom-react-usedebounce-hook-with-typescript/

Property based testing
https://github.com/dubzzz/fast-check/blob/master/documentation/1-Guides/HandsOnPropertyBased.md

Bundlers. Modules.
https://philipwalton.com/articles/using-native-javascript-modules-in-production-today/

View at Medium.com

An up-to-date article on HTML https://medium.com/actualize-network/modern-html-explained-for-dinosaurs-65e56af2981

And another one here: http://fastwebstart.com/modern-html-tutorial/

Lazy loading images BBC design
https://medium.com/bbc-design-engineering/native-lazy-loading-has-arrived-c37a165d70a5

Forms for react but is also framework agnostic. From the surgery of Redux forms

https://final-form.org/docs/react-final-form/getting-started

Why you should be trying to take CPU intensive tasks of the main thread and into a web worker.

https://dassur.ma/things/when-workers/

es-dev-server looks interesting

Developing without a build step

https://dev.to/open-wc/developing-without-a-build-2-es-dev-server-1cf5

Form data events

Web components

https://web.dev/more-capable-form-controls

https://dev.to/open-wc/developing-without-a-build-1-introduction-26ao

You don’t really need a build system. Vanilla js