For loops

Syntax

for loops provide a convenient short syntax for doing loops.

Let's see the same examples we saw for while loops in this new format.

js

for (let i = 1; i < 6; i++) {
  console.log(i)
}

console.log('Done!')

output

1
2
3
4
5
Done!

Accumulating a value

Let's add all the odd numbers less than 100.

js

let total = 0

for (let n = 1; n < 100; n += 2) {
  total += n
}

console.log(total)

output

2500

Looping through an array

We can still use i as a pointer to loop through an array.

js

function average(arr) {
  let total = 0

  for (let i = 0; i < arr.length; i++) {
    total += arr[i]
  }

  return total / arr.length
}

const ratings = [4.25, 3.34, 2.6, 2.74, 2.36, 2.32, 3.94, 2.73]
console.log(average(ratings))

output

3.035