Depends on the language. Since this year I am getting up to speed with JavaScript and TypeScript, and there are a lot of different notions around to learn. It r

Depends on the language. Since this year I am getting up to speed with JavaScript and TypeScript, and there are a lot of different notions around to learn. It really clicked for me just recently when I implemented my own little unit testing tool (https://www.npmjs.com/package/instatest https://www.npmjs.com/package/instatest). This touched many aspects of the ecosystem I needed to know about, and was yet pretty simple to do.