
📅 Day 4: Mastering Loops in JavaScript
Welcome to Day 4 of the challenge!
Today we unlock one of JavaScript’s most powerful tools: loops — a way to make your code do more with less.
A loop in JavaScript is a control structure that allows you to execute a block of code repeatedly as long as a specified condition is true.
Instead of writing repetitive code manually, loops help you automate tasks — like printing numbers, processing items in a list, or checking for conditions.
🏃 Why Loops?
Imagine you were asked to print numbers from 1 to 100.
Would you really write:
console.log(1);console.log(2);console.log(3);// ...console.log(100);
No way!
Instead, we use loops to repeat actions efficiently.
🔁 The 3 Main Loops in JavaScript
✅ 1. for loop
Great when you know how many times to repeat.
for (let i = 1; i <= 5; i++) { console.log("Step:", i);}
✅ 2. while loop
Used when you want to repeat while a condition is true.
let i = 1;while (i <= 5) { console.log("While Step:", i); i++;}
✅ 3. do...while loop
Runs at least once, even if the condition is false.
let i = 6;do { console.log("Do-While Step:", i); i++;} while (i <= 5);
⛔ break and continue
✅ break – exits the loop immediately
for (let i = 1; i <= 10; i++) { if (i === 5) break; console.log(i); // Stops at 4}
✅ continue – skips current iteration
for (let i = 1; i <= 5; i++) { if (i === 3) continue; console.log(i); // Skips 3}
✅ Mini Task:
Print All Even Numbers from 1 to 50
Your challenge: Loop from 1 to 50 and print only even numbers.
✅ Solution 1 (for loop):
for (let i = 1; i <= 50; i++) { if (i % 2 === 0) { console.log(i); }}
✅ Solution 2 (while loop):
let i = 2;while (i <= 50) { console.log(i); i += 2;}
❓ Interview Questions:
- What’s the difference between a for loop and a while loop?
- When would you prefer a do...while loop?
- What does break do inside a loop?
- What does continue do?
- Can you print numbers 1 to 100 using just one loop?
🎯 That’s a wrap for Day 4!
Tomorrow, in Day 5, we’ll explore Functions & Scope — a major step toward writing cleaner, reusable code.
Keep learning. Keep building. 💪
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