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Smriti Singh
Smriti Singh

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🧠 10-Day Challenge : Loops in JavaScript Day-4

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📅 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);
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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);
}
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✅ 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++;
}
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✅ 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);
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⛔ 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
}
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✅ continue – skips current iteration

for (let i = 1; i <= 5; i++) {
  if (i === 3) continue;
  console.log(i); // Skips 3
}
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✅ 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);
  }
}
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✅ Solution 2 (while loop):

let i = 2;
while (i <= 50) {
  console.log(i);
  i += 2;
}
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❓ Interview Questions:

  1. What’s the difference between a for loop and a while loop?
  2. When would you prefer a do...while loop?
  3. What does break do inside a loop?
  4. What does continue do?
  5. 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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