Custom eventsĬustom events occur inside the JavaScript core in Node.js. Side note: JavaScript does not have built-in capabilities to handle system events. The libuv library deals with lower-level events that are happening inside of the computer system, essentially, low-level events that come from the OS, such as receiving data from the internet, finished reading a file, and so on.īecause the flow of a Node.js program is determined by events (event-driven programming), all I/O requests would eventually generate a completion/failure event. System events occur from the C++ side of the Node.js core and are handled by a C library used in Node.js called libuv. There are two different types of events in Node.js, both of which we’ll cover in this article: 1.
Create the event emitter function constructor.Building a custom event emitter in Node.js.The general pattern for a custom event emitter.
#Nodejs eventemitter how to
In this article, we’ll discuss what event emitters are and why we should use them, as well as how to build custom event emitters. Since Node.js is based on JavaScript, it leverages this feature in its event-driven architecture. The JavaScript language enables us to respond to events by running code within an event handler. They are emitted due to either user activities, such as a mouse click or keystrokes, or directly from systems, such as errors or notifications. How to build custom Node.js event emittersĮditor’s note: This post was updated 13 September 2022 to include information about why one should use event emitters, the class members within EventEmitter, and make other general updates to the text.Įvents are actions that have software or hardware significance. Lawrence Eagles Follow Senior full-stack developer, writer, and instructor.
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