Loops

Loops repeat a block of code so you don't have to write it out by hand. The for loop is the workhorse when you know roughly how many times you want to repeat something:

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

A for loop has three parts separated by semicolons: an initializer (let i = 0), a condition checked before each pass (i < 5), and an update that runs after each pass (i++). The loop keeps running as long as the condition is true.

The while loop is simpler and better when you don't know the number of repetitions in advance — you just keep going while a condition holds:

let attempts = 0;
while (attempts < 3) {
  attempts = attempts + 1;
}

Be careful: if the condition in a while loop never becomes false, you've written an infinite loop, which will freeze whatever is running it. Always make sure something inside the loop moves you toward the exit condition.

Two keywords change a loop's flow mid-iteration:

• break exits the loop entirely, right away.
• continue skips the rest of the current iteration and jumps to the next one.

for (let i = 0; i < 10; i++) {
  if (i === 3) continue; // skip 3
  if (i === 6) break;    // stop entirely at 6
  console.log(i);
}
// logs 0, 1, 2, 4, 5

You'll also loop over arrays constantly — for (const item of someArray) reads naturally as "for each item of this array," and is usually clearer than tracking an index manually when you don't need the index itself.