Iterations

for ... of

for (const item of array) {
  console.log(item)
}

for item in array {
  print(item)
}

for ... of .entries

// arrays
for (const [index, item] of array.entries()) {
  console.log(index, item)
}

// objects
for (const [key, item] of Object.entries(object)) {
  console.log(key, item)
}

// arrays
for (index, item) in array.enumerated() {
  print(index, item)
}

// dictionaries
for (key, item) in dictionary {
  print(key, item)
}

.forEach

array.forEach((item, index) => {
  console.log(item, index)
})

// without index
array.forEach { item in
  print(item)
}

// with index
array.enumerated().forEach { (index, item) in
  print(item, index)
}

while

let i = 0
while (i < 3) {
  console.log(i)
  i++
}

var i = 0
while i < 3 {
  print(i)
  i += 1
}

for key in object

for (const key in object) {
  console.log(key)
}

for key in dictionary.keys {
  print(key)
}

See Objects ▶ Iterating for more examples when working with objects/dictionaries.

classical for loop

for (let i = 0; i < array.length; i++) {
  console.log(array[i])
}

for i in 0 ..< array.count {
  print(array[i])
}