for
Repeats a block of code with an initializer, condition, and update expression.
Syntax
for (init; condition; update) {
// ...
}
Examples
for (let i = 0; i < 3; i++) {
console.log(i);
}
Output
0
1
2
let sum = 0;
for (let i = 1; i <= 5; i++) {
sum += i;
}
console.log(sum);
Output
15
// Any clause may be omitted
let i = 0;
for (; i < 2; ) {
console.log(i);
i++;
}
Output
0
1
Notes
- Use `let` in the initializer to give each iteration its own binding,
which matters for closures.
- Use `break` to exit early and `continue` to skip to the next
iteration.
- For iterating values or object keys prefer `for...of` / `for...in`.
Browser & runtime support
| Environment | Since version |
|---|---|
| chrome | 1.0 |
| firefox | 1.0 |
| safari | 1.0 |
| edge | 12 |
| node | 0.10 |