Transform streams for processing in Node.js - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the Transform stream class from the 'stream' module.

Node.js

const { [1] } = require('stream');

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

AReadable

BDuplex

CWritable

DTransform

Attempts:

3 left

💡 Hint

Common Mistakes

Using Readable or Writable instead of Transform.

Forgetting to import from 'stream' module.

The Transform class is imported from the 'stream' module to create transform streams.

2fill in blank

medium

Complete the code to create a new Transform stream that converts input chunks to uppercase.

Node.js

const upperCaseTransform = new Transform({
  transform(chunk, encoding, callback) {
    this.push(chunk.toString().[1]());
    callback();
  }
});

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

AtoLowerCase

BtoUpperCase

Csplit

Dtrim

Attempts:

3 left

💡 Hint

Common Mistakes

Using toLowerCase instead of toUpperCase.

Forgetting to convert chunk to string before calling the method.

The toUpperCase() method converts the string chunk to uppercase.

3fill in blank

hard

Fix the error in the transform function to correctly handle asynchronous processing.

Node.js

const delayTransform = new Transform({
  async transform(chunk, encoding, callback) {
    await new Promise(resolve => setTimeout(resolve, 100));
    this.push(chunk);
    [1]();
  }
});

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

Acallback

Breturn

Cresolve

Ddone

Attempts:

3 left

💡 Hint

Common Mistakes

Not calling callback, causing the stream to hang.

Calling a non-existent function like done or resolve.

The callback() function must be called to signal that the transform step is done.

4fill in blank

hard

Fill both blanks to create a Transform stream that filters out chunks shorter than 5 characters.

Node.js

const filterShort = new Transform({
  transform(chunk, encoding, callback) {
    if (chunk.toString().[1] >= 5) {
      this.push(chunk);
    }
    [2]();
  }
});

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

Alength

Bsize

Ccount

Dcallback

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'size' or 'count' which are not string properties.

Forgetting to call callback(), causing the stream to stall.

The length property gives the string length, and callback() signals completion.

5fill in blank

hard

Fill all three blanks to create a Transform stream that appends '!' to each chunk and converts it to a string.

Node.js

const exclaimTransform = new Transform({
  transform(chunk, encoding, callback) {
    const modified = chunk.toString() + [1];
    this.push(modified.[2]());
    [3]();
  }
});

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

A'!'

BtoUpperCase

Ccallback

Dtrim

Attempts:

3 left

💡 Hint

Common Mistakes

Not appending the exclamation mark as a string.

Using trim instead of toUpperCase.

Forgetting to call callback().

We append '!' (option A), convert to uppercase (option B), and call callback() (option C) to finish.