Single-threaded non-blocking I/O concept in Node.js - Mini Project: Build & Apply

Understanding Single-threaded Non-blocking I/O in Node.js

📖 Scenario: You are building a simple Node.js program that reads two text files one after the other. You want to see how Node.js handles reading files without waiting for one to finish before starting the next.

🎯 Goal: Create a Node.js script that reads two files using non-blocking I/O and logs their contents to the console as soon as each is ready.

📋 What You'll Learn

Use the built-in fs module

Read two files named file1.txt and file2.txt

Use non-blocking asynchronous file reading

Log the contents of each file when it is read

Do not block the program while waiting for file reads

💡 Why This Matters

🌍 Real World

Many Node.js applications read files, databases, or network data without stopping the whole program. This makes apps faster and more responsive.

💼 Career

Understanding non-blocking I/O is essential for backend developers working with Node.js to build scalable and efficient servers.

1

Import the fs module

Write a line to import the built-in Node.js module fs using import syntax.

Node.js

# Import the fs module
# Your code here

Need a hint?

Use import { readFile } from 'fs'; to get the readFile function.

2

Create a function to read a file asynchronously

Write a function named readFileAsync that takes a filename parameter and uses readFile with a callback to read the file contents as UTF-8 text.

Node.js

import { readFile } from 'fs';

// Create readFileAsync function
# Your code here

Need a hint?

Use readFile(filename, 'utf8', callback) inside the function to read the file.

3

Call the function twice for two files

Call the readFileAsync function twice with the exact filenames 'file1.txt' and 'file2.txt' to start reading both files asynchronously.

Node.js

import { readFile } from 'fs';

function readFileAsync(filename) {
    readFile(filename, 'utf8', (err, data) => {
        if (err) {
            console.error(`Error reading ${filename}:`, err);
            return;
        }
        console.log(`Contents of ${filename}:`);
        console.log(data);
    });
}

// Call readFileAsync for file1.txt and file2.txt
# Your code here

Need a hint?

Call readFileAsync with 'file1.txt' and 'file2.txt' exactly.

4

Add a console log to show program continues

Add a line after the two calls to readFileAsync that logs 'Program continues without waiting for file reads.' to show the program does not block.

Node.js

import { readFile } from 'fs';

function readFileAsync(filename) {
    readFile(filename, 'utf8', (err, data) => {
        if (err) {
            console.error(`Error reading ${filename}:`, err);
            return;
        }
        console.log(`Contents of ${filename}:`);
        console.log(data);
    });
}

readFileAsync('file1.txt');
readFileAsync('file2.txt');

// Log that program continues
# Your code here

Need a hint?

Use console.log after the two function calls to show the program is not blocked.