for statement
The for construct sets a loop: a
code placed inside it will be repeated
a given number of times.
Syntax
for (initial commands; loop termination condition; commands after loop iteration) {
loop body
};
Example
Let's output a sequence of
numbers from 0
to 10:
for (let i = 0; i <= 10; i++) {
console.log(i);
}
Example
Let's output a sequence of
numbers from 10
to 0:
for (let i = 10; i >= 0; i--) {
console.log(i);
}
Example
Let's output even numbers
from 0 to 10:
for (let i = 2; i <= 10; i += 2) {
console.log(i);
}
Example
Let's output array elements:
let arr = ['a', 'b', 'c', 'd', 'e'];
for (let i = 0; i < arr.length; i++) {
console.log(arr[i]);
}
Example
The initial commands and commands after loop iteration may consist of not one, but several commands separated by commas. For example, let's make two counters: let the first one increase by one each loop iteration, and the second one - by two:
for (let i = 0, j = 0; i <= 9; i++, j += 2) {
console.log(i, j);
}
See also
-
the lesson from JavaScript tutorial
detailing how to work with theforloop -
the
for-ofstatement
that creates a loop to iterate over an array -
the
for-instatement
that creates a loop to iterate over an object -
the
whilestatement
that also creates a loop -
the
breakstatement
that breaks a loop -
the
continuestatement
that moves a loop to next iteration