The document discusses how to use RxJS (Reactive Extensions library for JavaScript) to treat events like arrays by leveraging Observable types and operators. It explains key differences between Observables and Promises/Arrays, how Observables are lazy and cancelable unlike Promises. Various RxJS operators like map, filter, interval and fromEvent are demonstrated for transforming and composing Observable streams. The document aims to illustrate how RxJS enables treating events as collections that can be processed asynchronously over time.