MEAN Node.js Async Patterns and Performance 3

Question 1

What is PM2 and why is it commonly used with Node.js MEAN stack applications?

Accepted Answer

A process manager that keeps Node.js apps running, handles restarts, clustering, and log management

Answer

A package manager alternative to npm for Node.js

Answer

A performance monitoring tool for MongoDB metrics

Answer

A proxy manager for load balancing Express servers

Question 2

What is the Node.js `--inspect` flag used for?

Accepted Answer

Enables the V8 Inspector protocol for debugging Node.js with Chrome DevTools or VS Code

Answer

Inspects npm package dependencies for vulnerabilities

Answer

Validates the syntax of a JavaScript file without running it

Answer

Displays detailed error stack traces in production

Question 3

What does connection pooling do for MongoDB in a Node.js application?

Accepted Answer

Reuses a set of pre-established database connections rather than creating a new one for each query

Answer

Distributes queries across multiple MongoDB servers

Answer

Caches query results to reduce database load

Answer

Limits the number of concurrent MongoDB operations

Question 4

What is the purpose of environment variables in a Node.js MEAN application?

Accepted Answer

Store configuration and secrets outside the codebase, accessed via process.env

Answer

Pass data between Node.js processes and threads

Answer

Configure the Node.js runtime version and memory limits

Answer

Define available npm scripts for the project

Question 5

What is graceful shutdown in a Node.js Express server?

Accepted Answer

Completing in-flight requests before exiting when receiving SIGTERM, preventing abrupt connection drops

Answer

Gradually reducing server load before a planned maintenance window

Answer

Saving server state to disk before shutting down

Answer

Closing all database connections before process exit

Question 6

What does the `NODE_ENV` environment variable control in a MEAN stack application?

Accepted Answer

Configures behavior for different environments: development enables verbose errors; production enables optimizations

Answer

Sets the Node.js version to use for the application

Answer

Defines which npm scripts are available for each environment

Answer

Controls which MongoDB database to connect to