I front-end today, we are almost always dealing with abstractions - a framework mediates our interaction with the DOM, a library wraps our events, heck, we even have a library enforcing types. Even though we don’t always see it, underneath it all is still good-old JavaScript and web APIs, and it’s worthwhile to know what our abstractions ultimately translate to. Not only will it make us better developers, not only will it make us better “abstraction-users”, but also - it’s something we are all completely capable of. So let’s dive into two such abstractions - ReactJS’s component lifecycle and Angular’s EventEmitter - and look at the source code and the nuts and bolts that make them possible.