Loops

Writing console.log(1); console.log(2); console.log(3); ... up to 1000 is a nightmare. Loops fix that — they let you run the same block of code over and over, usually with a variable that changes each time.

What you'll learn

• Write a for loop with a counter
• Write a while loop with a stop condition
• Pick the right one for the job

Instructions

Use a for loop to print the numbers 1 through 5, each on its own line:

1
2
3
4
5

Your solution must use a for loop.

Key concepts

The for loop

for is three things separated by semicolons: where to start, when to keep going, and what to change each step.

for (let i = 0; i < 3; i++) {
  console.log(i);
}
// prints: 0, 1, 2

• let i = 0 — initialize the counter (runs once before the loop starts)
• i < 3 — keep going while this is true (checked before each iteration)
• i++ — shorthand for i = i + 1, runs after each iteration

The while loop

while is simpler: just a condition. The loop keeps running until the condition is false.

let n = 100;
while (n > 1) {
  n = n / 2;
  console.log(n);
}

Use while when the number of iterations depends on logic inside the loop, not a known count upfront.

Don't forget to change the variable

This is an infinite loop:

let i = 0;
while (i < 5) {
  console.log(i);
  // oops — never changed i
}

If the loop body doesn't change the variable in the condition, it runs forever.

Hints

1. Start at 1 and stop after 5.
2. for (let i = 1; i <= 5; i++) { ... }
3. Inside the body: console.log(i);