Day 6 Loops — for, while, forEach
Loop se ek kaam baar baar karte hain bina code repeat kiye. 100 students ke marks print karne hain? Loop se sirf kuch lines mein ho jaata hai.
for Loop
Jab exact count pata ho tab for loop use karo.
// Counting 1 to 5
for (let i = 1; i <= 5; i++) {
console.log("Count:", i);
}
// Count: 1, 2, 3, 4, 5
// Reverse counting
for (let i = 5; i >= 1; i--) {
console.log(i);
}
// Even numbers
for (let i = 2; i <= 10; i += 2) {
console.log(i); // 2, 4, 6, 8, 10
}
while Loop
Jab count pata na ho, condition pe loop chalao.
let attempts = 0;
while (attempts < 3) {
console.log("Attempt:", attempts + 1);
attempts++;
}
// do-while — pehle chalao, phir condition check karo
let count = 0;
do {
console.log("Running...", count);
count++;
} while (count < 3);
Loop Control — break & continue
break loop rok deta hai, continue next iteration skip karta hai.
// break — loop rok do
for (let i = 0; i < 10; i++) {
if (i === 5) break; // 5 par rok do
console.log(i); // 0, 1, 2, 3, 4
}
// continue — yeh step skip karo
for (let i = 0; i < 6; i++) {
if (i === 3) continue; // 3 skip
console.log(i); // 0, 1, 2, 4, 5
}
🎯 Practice Challenge
1 se 100 tak saare even numbers ka sum calculate karo using a loop.