The "Learn JavaScript in Construct" tutorial is still a work in progress - there are several more parts to come and it will cover more of the things you've mentioned.
The guide also already covers some things like how => is another syntax for functions. The most recent part does also cover (albeit in brief) how addEventListener is a standard way to listen for events in the JavaScript ecosystem: for example document.addEventListener("click", func) means func will be called every time the user clicks anywhere in the page.
This is all the usual way things are done with JavaScript, including in browsers and other environments like node.js. So while there may be a learning curve as many of the patterns and APIs will differ from GameMaker, you're learning the real-world patterns used widely in industry, which is a really useful transferable skill.
Further many of these patterns are very powerful and allow for complex and sophisticated code that can make things easy that are currently awkward in GML. For example async functions make it far, far easier to write async code. However that does mean, naturally, learning about how async functions work in JavaScript, but again this is all industry standard stuff so you'll be learning real-world programming skills, rather than one tool's specific way of doing things.