You asked: How does EventEmitter work Javascript?

What is EventEmitter in js?

Node. js allows us to create and handle custom events easily by using events module. Event module includes EventEmitter class which can be used to raise and handle custom events. The following example demonstrates EventEmitter class for raising and handling a custom event.

How does EventEmitter work in NodeJS?

EventEmitter is a class that helps us create a publisher-subscriber pattern in NodeJS. With an event emitter, we can simply raise a new event from a different part of an application, and a listener will listen to the raised event and have some action performed for the event.

Should I use EventEmitter?

Event emitters and listeners are crucial to NodeJS development, and many other programming languages development. They are very useful when you have some function that needs to execute “whenever this other thing happens”, without requiring that function to finish or even work for that matter.

What is the use of EventEmitter?


Use in components with the @Output directive to emit custom events synchronously or asynchronously, and register handlers for those events by subscribing to an instance.

What is Libuv in Nodejs?

libuv is a multi-platform C library that provides support for asynchronous I/O based on event loops. It supports epoll(4) , kqueue(2) , Windows IOCP, and Solaris event ports. It is primarily designed for use in Node. js but it is also used by other software projects.

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What is EventEmitter on property?

EventEmitter provides multiple properties like on and emit. on property is used to bind a function with the event and emit is used to fire an event.

Which special object is an instance of EventEmitter Nodejs?

EventEmitter Class. The event module contains the EventEmitter class. The Util package provides a way to inherit from one class to another class. The “EventEmitter” class allows us to listen for events and assign actions to run when those events occur.

How do you get parallelism in node JS?

Node can support “Parallelism” via either the Cluster or child_process modules packaged in the Nodejs Core API. Both of these modules create additional processes and not additional threads. Also, this is great question on Threads and Pooling which has a lot of detail.

How does an event loop work?

The event loop works by making a request to some internal or external “event provider” (that generally blocks the request until an event has arrived), then calls the relevant event handler (“dispatches the event”). … The event loop almost always operates asynchronously with the message originator.

Why do we need event emitter?

Event Emitter is a module that facilitates communication between objects in Node. … js uses EventEmitter Since Node. js follows the Event-Driven Architecture. That is to say, we will learn Event Emitter by building a custom logger using Event Emitter in this article.

What is difference between subject and EventEmitter?

There is not much difference. EventEmitter extends Subject . The Angular2 team stressed the fact though, that EventEmitter should not be used for anything else then @Output() s in components and directives.

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