Reading data with Readable streams in Node.js - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a Readable stream in Node.js?

A Readable stream is a source of data that you can read from in chunks, like reading a file or receiving data over the network. It lets you process data piece by piece instead of loading it all at once.

beginner

How do you start reading data from a Readable stream in Node.js?

You can listen to the 'data' event on the stream to get chunks of data as they arrive. For example: stream.on('data', chunk => { /* use chunk */ });

beginner

What does the 'end' event on a Readable stream signify?

The 'end' event means the stream has no more data to provide. It tells you that reading is finished.

intermediate

What is the difference between flowing mode and paused mode in Readable streams?

In flowing mode, data is read automatically and emitted via 'data' events. In paused mode, you must call stream.read() to get data manually.

intermediate

How can you read all data from a Readable stream using async/await?

You can use a for-await-of loop to read chunks asynchronously: for await (const chunk of stream) { /* process chunk */ }

Which event do you listen to for receiving chunks of data from a Readable stream?

A 'data'

B 'end'

C 'error'

D 'close'

The 'data' event is emitted whenever a chunk of data is available to read.

What does the 'end' event on a Readable stream indicate?

A An error occurred

B Data is flowing

C The stream is paused

D The stream has no more data

The 'end' event signals that the stream has finished sending all data.

How do you switch a Readable stream to flowing mode?

A Call stream.pause()

B Call stream.resume() or add a 'data' event listener

C Call stream.read() repeatedly

D Call stream.close()

Adding a 'data' event listener or calling stream.resume() makes the stream flow automatically.

Which syntax allows reading data from a Readable stream using async/await?

A for await (const chunk of stream) { }

B stream.on('data', chunk => { })

C stream.read()

D stream.pipe()

The for-await-of loop lets you asynchronously iterate over chunks from the stream.

What happens if you do not listen to 'data' or call stream.read() on a Readable stream?

A The stream will emit data anyway

B The stream will close immediately

C The stream will stay in paused mode and not emit data

D The stream will throw an error

Without reading, the stream stays paused and does not emit data chunks.

Explain how to read data from a Readable stream in Node.js using event listeners.

Think about how you get pieces of data and know when the stream finishes.

Describe the difference between flowing and paused modes in Readable streams and how to switch between them.

Consider how the stream sends data and how you control it.