@immutable-array/copy-within NPM

@immutable-array/copy-within

Immutable Array.prototype.copyWithin().

Install

Install with npm:

npm install @immutable-array/copy-within

Usage

Same API with Array.prototype.copyWithin()

/**
 * Returns the this object after copying a section of the array identified by start and end
 * to the same array starting at position target
 * @param array Base array
 * @param target If target is negative, it is treated as length+target where length is the
 * length of the array.
 * @param start If start is negative, it is treated as length+start. If end is negative, it
 * is treated as length+end.
 * @param end If not specified, length of the this object is used as its default value.
 */
export declare function copyWithin<T>(array: Array<T>, target: number, start: number, end?: number): Array<T>;

Example

import { copyWithin } from "@immutable-array/copyWithin";
const originalArray = [1, 2, 3, 4, 5];
assert.deepStrictEqual(copyWithin(originalArray, -2), [1, 2, 3, 1, 2]);
assert.deepStrictEqual(copyWithin(originalArray, 0, 3), [4, 5, 3, 4, 5]);
assert.deepStrictEqual(copyWithin(originalArray, 0, 3, 4), [4, 2, 3, 4, 5]);
assert.deepStrictEqual(copyWithin(originalArray, 0, -2, -1), [4, 2, 3, 4, 5]);

TODO: Array-like.

This is not specified behavior.

If you interesting in this, Please comment to copyWithIn() with Array-like · Issue #20 · azu/immutable-array-prototype.

import { copyWithin } from "@immutable-array/copyWithin";
const arrayLike = { length: 5, 3: 1 };
let actual = copyWithin(arrayLike, 0, 3);
assert.deepStrictEqual(actual, [1, , , 1,]);