Event-driven architecture in Express - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is event-driven architecture in Express?

It is a design where the app reacts to events like user actions or messages by running specific code called event handlers.

intermediate

How does Express handle events internally?

Express uses Node.js's EventEmitter to listen for and respond to events like HTTP requests.

beginner

What is an event emitter in Express?

An event emitter is an object that sends out signals (events) that other parts of the app can listen to and react upon.

beginner

Why use event-driven architecture in web apps?

It helps apps respond quickly and efficiently to user actions or system changes without waiting, making apps more interactive and scalable.

intermediate

Give an example of an event-driven pattern in Express.

Using middleware functions that listen for HTTP request events and process them step-by-step is an event-driven pattern.

What does an event emitter do in Express?

A Handles CSS styling

B Stores data in a database

C Renders HTML pages

D Sends out events for other parts to listen to

Event emitters send out events that listeners can react to.

Which Node.js module is key for event-driven programming in Express?

A events

B http

C fs

D path

The 'events' module provides EventEmitter used in event-driven design.

What triggers event handlers in Express?

A CSS changes

B User actions or system events

C Database schema updates

D Image uploads only

Event handlers run when events like user clicks or requests happen.

Middleware in Express is an example of what architecture style?

A Event-driven

B Client-server

C Batch processing

D Monolithic

Middleware listens for request events and processes them stepwise.

Why is event-driven architecture good for scalability?

A It processes events one by one slowly

B It uses more memory

C It allows handling many events independently and quickly

D It requires less code comments

Handling events independently helps apps scale better.

Explain how event-driven architecture works in Express and why it is useful.

Think about how Express reacts to HTTP requests as events.

Describe the role of middleware in Express's event-driven architecture.

Middleware functions run in order when a request event happens.