Jest

Typescript

Tailwind

<aside> 💡 nearly all pages on the web are built on three core languages, each of which serves a slightly different purpose:

  1. HTML, or HyperText Markup Language, which is used to describe the content of websites;
  2. CSS, Cascading Style Sheets, which is used to describe the aesthetics of websites; and
  3. JavaScript, which is used to make websites interactive and dynamic. </aside>

For fairly comprehensive guides, check out these tutorials:

AJAX documentation

HTML Living Standard (contains a bunch of standard HTML entities)