Loops

Loops let you repeat a block of code multiple times, either a fixed number of times or until a condition fails.

1. for Loop

Use when the number of iterations is known.

for (let i = 0; i < 5; i++) {
  console.log(i);
}

• i = 0 → start
• i < 5 → condition
• i++ → increment

2. while Loop

Runs while the condition is true.

let i = 0;
while (i < 5) {
  console.log(i);
  i++;
}

3. do...while Loop

Runs at least once, then checks the condition.

let i = 0;
do {
  console.log(i);
  i++;
} while (i < 5);

4. for...of Loop

Iterates over iterables like arrays, strings, etc.

let nums = [10, 20, 30];

for (let num of nums) {
  console.log(num);
}

5. for...in Loop

Iterates over keys in an object.

const user = { name: "John", age: 30 };

for (let key in user) {
  console.log(key, user[key]);
}

6. break and continue

break: exits the loop early.

for (let i = 0; i < 10; i++) {
  if (i === 5) break;
  console.log(i); // 0 to 4
}

continue: skips current iteration.

for (let i = 0; i < 5; i++) {
  if (i === 2) continue;
  console.log(i); // 0, 1, 3, 4
}

7. Looping Arrays with .forEach()

let arr = [1, 2, 3];

arr.forEach(function (val) {
  console.log(val);
});