Events vs callbacks decision in Node.js - Quick Revision & Key Differences

Recall & Review

beginner

What is a callback in Node.js?

A callback is a function passed as an argument to another function, which is called after a task completes to handle the result or error.

beginner

What is an event in Node.js?

An event is a signal emitted by an object to indicate that something happened, which listeners can respond to asynchronously.

intermediate

When should you prefer events over callbacks?

Use events when you want to handle multiple occurrences or when many parts of your program need to react to the same action.

intermediate

What is a downside of using callbacks?

Callbacks can lead to complex nested code, often called "callback hell," making code harder to read and maintain.

intermediate

How do events improve code organization compared to callbacks?

Events separate the event emitter from the event handlers, allowing cleaner, modular code where multiple listeners can respond independently.

Which Node.js feature allows multiple listeners to respond to the same action?

A Callbacks

B Events

C Promises

D Synchronous functions

Events allow multiple listeners to respond to the same emitted signal.

What is a common problem when using many nested callbacks?

A Callback hell

B Event loop blocking

C Memory leaks

D Synchronous execution

Nested callbacks can cause "callback hell," making code hard to read.

When should you use a callback instead of an event?

A For a single, one-time asynchronous task

B When multiple parts need to react to the same event

C For synchronous code

D When you want to emit signals

Callbacks are best for handling single asynchronous operations.

Which Node.js module is commonly used to work with events?

A path

B fs

C http

D events

The 'events' module provides the EventEmitter class for event handling.

What is a benefit of using events in Node.js?

A Makes code synchronous

B Prevents any errors

C Allows multiple listeners to respond independently

D Simplifies synchronous loops

Events allow multiple listeners to respond independently to the same event.

Explain the difference between events and callbacks in Node.js and when to use each.

Think about how many parts of your code need to react and how often.

Describe a scenario where using events is better than callbacks and why.

Imagine a party where many friends react to the same music.