@rbxts/jsnatives

Array.slice

Returns a shallow copy of a portion of an array into a new array.

Signature

function slice<T>(array: Array<T>, start?: number, end?: number): Array<T>

Description

The Array.slice() method returns a shallow copy of a portion of an array into a new array object. It selects elements from start index up to, but not including, end index. The original array is not modified.

Parameters:

array: The array to slice
start (optional): Zero-based index at which to start extraction. Defaults to 0.
- If negative, it indicates an offset from the end of the array.
- If start >= array.length, an empty array is returned.
end (optional): Zero-based index before which to end extraction. Defaults to array.length.
- If negative, it indicates an offset from the end of the array.
- If end >= array.length or omitted, slice extracts through the end of the array.

Examples

Basic usage

const array = [1, 2, 3, 4, 5];
const sliced = ArrayUtils.slice(array, 1, 4);

print(array); // [1, 2, 3, 4, 5] - original array is unchanged
print(sliced); // [2, 3, 4] - new array containing elements from index 1 up to (but not including) index 4

Using negative indices

const array = [1, 2, 3, 4, 5];

// Start from the 2nd to last element, go until the end
const sliced1 = ArrayUtils.slice(array, -2);
print(sliced1); // [4, 5]

// Start from the 3rd element, end at the 2nd to last element
const sliced2 = ArrayUtils.slice(array, 2, -1);
print(sliced2); // [3, 4]

// Start from the 3rd to last element, end at the last element
const sliced3 = ArrayUtils.slice(array, -3, -1);
print(sliced3); // [3, 4]

Omitting parameters

const array = [1, 2, 3, 4, 5];

// Omitting both parameters returns a copy of the entire array
const fullCopy = ArrayUtils.slice(array);
print(fullCopy); // [1, 2, 3, 4, 5]
print(array === fullCopy); // false - they are different array references

// Specifying only start returns from that index to the end
const fromSecond = ArrayUtils.slice(array, 1);
print(fromSecond); // [2, 3, 4, 5]

Slicing with indices beyond array boundaries

const array = [1, 2, 3];

// If start is beyond the array length, an empty array is returned
const empty = ArrayUtils.slice(array, 5);
print(empty); // []

// If end is beyond the array length, extraction goes to the end of the array
const toEnd = ArrayUtils.slice(array, 1, 10);
print(toEnd); // [2, 3]

Shallow copy behavior

const array = [
  { id: 1, name: "Alice" },
  { id: 2, name: "Bob" },
  { id: 3, name: "Charlie" }
];

const sliced = ArrayUtils.slice(array, 0, 2);

// Modifying the original nested object affects the sliced array too
array[0].name = "Modified Alice";

print(array[0].name); // "Modified Alice"
print(sliced[0].name); // "Modified Alice" - objects are shared by reference