for, while, do...while, for...of and for...in.
✍️ 3 exercises + code challenge in this lessonLoops repeat a block of code.
for (let i = 0; i < 5; i++): a fixed number of times.while (condition): while a condition is true.do { } while (condition): runs at least once.for (const item of array): each value of an iterable (arrays, strings).for (const key in object): each key of an object.break exits a loop early; continue skips to the next iteration.
Mastering JavaScript Loops helps you write clean and reliable JavaScript code. Follow standard conventions, test edge cases, and keep logic simple. Try running the code example below and complete the exercises to build confidence.
<pre id="out"></pre>
<script>
const log = (...a) => document.getElementById("out").textContent += a.join(" ") + "\n";
for (let i = 1; i <= 5; i++) {
log("7 x", i, "=", 7 * i);
}
let n = 3;
while (n > 0) { log("Countdown", n); n--; }
for (const lang of ["HTML", "CSS", "JS"]) log("Learning", lang);
const scores = { ali: 80, sara: 92 };
for (const name in scores) log(name, "→", scores[name]);
for (let i = 1; i <= 10; i++) {
if (i % 2 === 0) continue;
if (i > 7) break;
log("odd:", i);
}
</script>Check what you learned in “JavaScript Loops”.
Loop over each value of the array.
for (const item items) { log(item); }
Which statement skips to the next loop iteration?
Use a loop to log the numbers 1 to 5, each on its own line.
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