Array

The Array type represents a list of values. An array can contain any type of value, including other arrays. An array can be modified after it is created - elements can be added, removed or replaced.

Reading and writing

Use the [] syntax to create an array, and then the subscript [] operator to read and write elements:

let array = [123, 456, 789]
array[1] // read element 1: outputs 456
array[1] = 999 // replace element 1 with 999, array is now [123, 999, 789]

Pushing and popping elements

You can add elements to the end of an array using the Push method,

let array = [123]
array.Push(456).Push(789) // array is now [123, 456, 789]

Remove the last element from an array using the Pop method:

let array = [123, 456, 789]
let last = array.Pop() // last is 789, array is now [123, 456]

Deleting elements

Use the delete keyword to remove an element from an array. This replaces the value with undefined but does not change the length of the array:

let array = [123, 456, 789]
delete array[1] // array is now [123, undefined, 789]

Deleting an element returns its previous value, or undefined if the element did not exist:

let array = [123, 456, 789]
let value = delete array[1] // value is 456
let value2 = delete array[5] // value2 is undefined

Iterating

You can iterate over each element in an array using a for loop:

let array = [123, 456, 789]
for value in array {
    Transmission { %(value) }
}
// Outputs 123, 456, 789

You can also provide two loop variables to iterate over the index and value of an Array:

let list = ["Potato", "Tomato", "Banana"]
for index, value in list {
    Transmission { %(index + ": " + value) }
}
// Outputs "0: Potato", "1: Tomato", "2: Banana"

Concatenation

You can concatenate arrays using the + operator. This will create a new array consisting of the elements of the first array followed by the elements of the second array:

let a = [1, 2, 3]
let b = [4, 5, 6]
let c = a + b // c is [1, 2, 3, 4, 5, 6]

If you want to add new elements to an existing array, it is better to use the PushAll functions as that does not require creating a new array:

let a = [1, 2, 3]
let b = [4, 5, 6]
a.PushAll(b) // a is now [1, 2, 3, 4, 5, 6]

Constant arrays

Some arrays are constant. That is, they are generated at compile time and cannot be changed at runtime. This can improve the performance of your game.

In particular, arrays generated using the Asset wildcard syntax are constant:

let images = @images/fireball-*.svg
let frame0 = images[0] // e.g. @fireball-0.svg
images[0] = @thunderbolt.svg // error: cannot modify a constant array