Event loop mental model in Node.js - Mini Project: Build & Apply

Understanding the Node.js Event Loop

📖 Scenario: You are building a simple Node.js script that demonstrates how the event loop handles asynchronous tasks like timers and immediate callbacks.

🎯 Goal: Create a Node.js script that sets up a timer and an immediate callback, then logs messages to show the order in which they run, helping you understand the event loop.

📋 What You'll Learn

Create a variable called message with the value 'Start'.

Create a variable called delay with the value 100 (milliseconds).

Use setTimeout with delay and a callback that logs 'Timeout finished'.

Use setImmediate with a callback that logs 'Immediate finished'.

💡 Why This Matters

🌍 Real World

Node.js uses the event loop to handle many tasks without waiting, making it great for servers that handle many users at once.

💼 Career

Understanding the event loop is essential for Node.js developers to write efficient, non-blocking code and debug asynchronous behavior.

1

DATA SETUP: Create initial variables

Create a variable called message and set it to the string 'Start'.

Node.js

// Create a variable called message and set it to 'Start'
// Your code here

Need a hint?

Use const to create a variable named message and assign it the string 'Start'.

2

CONFIGURATION: Add a delay variable

Create a variable called delay and set it to the number 100.

Node.js

const message = 'Start';
// Create a variable called delay and set it to 100
// Your code here

Need a hint?

Use const to create a variable named delay and assign it the number 100.

3

CORE LOGIC: Set up a timer with setTimeout

Use setTimeout with the delay variable and a callback function that logs 'Timeout finished'.

Node.js

const message = 'Start';
const delay = 100;
// Use setTimeout with delay and a callback that logs 'Timeout finished'
// Your code here

Need a hint?

Use setTimeout with an arrow function callback that calls console.log with 'Timeout finished'.

4

COMPLETION: Add setImmediate callback

Use setImmediate with a callback function that logs 'Immediate finished'.

Node.js

const message = 'Start';
const delay = 100;
setTimeout(() => {
  console.log('Timeout finished');
}, delay);
// Use setImmediate with a callback that logs 'Immediate finished'
// Your code here

Need a hint?

Use setImmediate with an arrow function callback that calls console.log with 'Immediate finished'.