When I was young, I was thrilled to discover I could cancel HTTP requests using cancelToken. However, it took me a month to realize that this didn't actually help reduce server load. These days, developers are quite enthusiastic about AbortController and AbortSignal. Some influential developers discovered that AbortController could be used not just for cancelling fetch requests, but for nearly any event. Soon after, social media became filled with articles about AbortController - to the point where not writing about it seemed to suggest you weren't a proper frontend developer.
I agreed that these features are great and fun, but as a developer, we should not only know what is it, but also know how it works.
Let's start from the basic use case: cancel a fetch request.