Node.js Database Integration 5

Question 1

What is the purpose of `mongoose.connection.on('error', handler)` in a Node.js application?

Accepted Answer

To catch post-connection errors such as network drops

Answer

This event listener catches connection-level errors that occur after the initial connection is established, like network interruptions.

Question 2

In Sequelize, what is the difference between `Model.create()` and `Model.build()` + `instance.save()`?

Accepted Answer

`create()` combines build and save in one call; `build()` creates an unsaved instance

Answer

`Model.create()` is a convenience method that builds and persists in one step, while `build()` creates an in-memory instance you must manually `save()`.

Question 3

Which Redis command atomically increments an integer value stored at a key?

Accepted Answer

client.incr('counter')

Answer

`INCR` atomically increments the integer value at a key by 1, making it safe for concurrent access without locks.

Question 4

In Prisma, what is a `select` clause used for in a `findMany` call?

Accepted Answer

Choosing which fields to include in the result

Answer

The `select` option lets you specify exactly which fields Prisma should return, reducing payload size.

Question 5

What does enabling `WAL mode` (Write-Ahead Logging) in SQLite improve for a Node.js application?

Accepted Answer

Concurrent read performance while a write is in progress

Answer

WAL mode allows reads and writes to occur concurrently without blocking each other, which is critical for web servers.

Node.js Practice Test

Node.js Practice Test

Node.js Database Integration 5