The Observer Pattern: The EventEmitter Class
Explore the core concepts of the Observer pattern in Node.js through the EventEmitter class. Understand its methods for registering, emitting, and managing listeners in asynchronous programming. Learn how to handle events and errors efficiently, reinforcing best practices for reactive application design.
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Another important and fundamental pattern used in Node.js is the Observer pattern. Together with the Reactor pattern and callbacks, the Observer pattern is an absolute requirement for mastering the asynchronous world of Node.js.
The Observer pattern is the ideal solution for modeling the reactive nature of Node.js and a perfect complement for callbacks.
The Observer pattern defines an object (called subject) that can notify a set of observers (or listeners) when a change in its state occurs.
The main difference from the Callback pattern is that the subject can actually notify multiple observers, while a traditional CPS callback will usually propagate its result to only one listener, the callback.
The EventEmitter class
In traditional ...