for

for (let i = 0; i < 3; i = i + 1)
  console.log(i)

>0
>1
>2

for of

const persons = ['A', 'B', 'C']
for (const person of persons) {
  console.log(person);
}
>'A'
>'B'
>'C'

for in

const persons = ['A', 'B', 'C']
for (const person in persons) {
  console.log(person);
}
>'0'
>'1'
>'2'

const persons = ['A', 'B', 'C']
for (const index in persons) {
  const person = persons[index];
  console.log(person);
}
>'A'
>'B'
>'C'