Event loop phases and timer execution in Node.js - Mini Project: Build & Apply

Understanding Event Loop Phases and Timer Execution in Node.js

📖 Scenario: You are building a simple Node.js script to understand how timers and the event loop phases work together. This will help you see when different timers execute in relation to each other.

🎯 Goal: Create a Node.js script that sets up timers using setTimeout and setImmediate, and logs messages to show the order in which they run during the event loop phases.

📋 What You'll Learn

Create a variable to hold a message string

Add a delay time variable for the timer

Use setTimeout to schedule a callback that logs the message

Use setImmediate to schedule a callback that logs a different message

💡 Why This Matters

🌍 Real World

Understanding the event loop helps you write efficient Node.js code that handles timers and asynchronous tasks correctly.

💼 Career

Node.js developers must know event loop behavior to avoid bugs and optimize performance in server-side applications.

1

Create a message variable

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

Node.js

// Your code here

Need a hint?

Use const to create a variable named message and assign the exact string 'Timer executed'.

2

Add a delay time variable

Add a variable called delay and set it to the number 100 to represent milliseconds.

Node.js

const message = 'Timer executed';
// Your code here

Need a hint?

Create a const variable named delay and assign it the number 100.

3

Schedule a setTimeout callback

Use setTimeout with a callback function that logs the message variable, and use the delay variable as the timeout duration.

Node.js

const message = 'Timer executed';
const delay = 100;
// Your code here

Need a hint?

Call setTimeout with an arrow function that logs message, and pass delay as the second argument.

4

Schedule a setImmediate callback

Use setImmediate with a callback function that logs the string 'Immediate executed'.

Node.js

const message = 'Timer executed';
const delay = 100;
setTimeout(() => {
  console.log(message);
}, delay);
// Your code here

Need a hint?

Call setImmediate with an arrow function that logs the exact string 'Immediate executed'.