Stream backpressure concept in Node.js - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a readable stream from a file.

Node.js

const fs = require('fs');
const readable = fs.createReadStream('[1]');

Drag options to blanks, or click blank then click option'

A'input.txt'

B'output.txt'

C'data.json'

D'log.txt'

Attempts:

3 left

💡 Hint

Common Mistakes

Using an output file name instead of input file name.

Forgetting to put quotes around the file name.

The fs.createReadStream function needs the input file name to read data from. Here, 'input.txt' is the correct file to read.

2fill in blank

medium

Complete the code to pause the readable stream when the buffer is full.

Node.js

readable.on('data', (chunk) => {
  if (!writable.write(chunk)) {
    readable.[1]();
  }
});

Drag options to blanks, or click blank then click option'

Apause

Bstop

Chalt

Dend

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'stop' or 'end' which are not valid readable stream methods.

Using 'halt' which is not a method on streams.

The pause() method pauses the readable stream to apply backpressure when the writable stream buffer is full.

3fill in blank

hard

Fix the error in the code to resume the readable stream when the writable stream drains.

Node.js

writable.on('drain', () => {
  readable.[1]();
});

Drag options to blanks, or click blank then click option'

Apause

Bstop

Cresume

Dend

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'pause' again instead of 'resume'.

Using 'stop' or 'end' which do not resume streams.

The resume() method restarts the readable stream after it was paused due to backpressure.

4fill in blank

hard

Fill both blanks to correctly handle backpressure in a pipe.

Node.js

readable.on('data', (chunk) => {
  if (!writable.[1](chunk)) {
    readable.[2]();
  }
});

Drag options to blanks, or click blank then click option'

Awrite

Bpause

Cend

Ddestroy

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'end' or 'destroy' instead of 'write' for sending data.

Using 'end' or 'destroy' instead of 'pause' to stop reading.

The write() method writes data to the writable stream. If it returns false, the readable stream should pause() to apply backpressure.

5fill in blank

hard

Fill all three blanks to create a backpressure-aware stream pipe.

Node.js

readable.on('data', (chunk) => {
  if (!writable.[1](chunk)) {
    readable.[2]();
  }
});
writable.on('[3]', () => {
  readable.resume();
});

Drag options to blanks, or click blank then click option'

Awrite

Bpause

Cdrain

Dend

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'end' event instead of 'drain' for writable readiness.

Using 'stop' or 'destroy' methods which do not exist on streams.

This code writes chunks to the writable stream. If write() returns false, it pauses the readable stream. When the writable stream emits drain, it resumes the readable stream.