array-copyWithin

Polyfill for Array.prototype.copyWithin.

The copyWithin() method copies the sequence of array elements within the array to the position starting at target. The copy is taken from the index positions of the second and third arguments start and end. The end argument is optional and defaults to the length of the array.

Install

$ npm install --save copyWithin

Usage

var copyWithin = require('array-copyWithin');

copyWithin([1, 2, 3, 4, 5], 0, 3);
// => [4, 5, 3, 4, 5]

copyWithin([1, 2, 3, 4, 5], 0, 3, 4);
// => [4, 2, 3, 4, 5]

copyWithin([1, 2, 3, 4, 5], 0, -2, -1);
// => [4, 2, 3, 4, 5]

copyWithin({ length: 5, 3: 1, 4: 0 }, 0, 3);
// => {0: 1, 1: 0, 3: 1, 4: 0, length: 5 }

API

copyWithin(array, start[, end = array.length])

target - Target start index position where to copy the elements to.

start - Source start index position where to start copying elements from.

end - Optional. Source end index position where to end copying elements from.

The arguments target, start, and end are coerced to Number and truncated to integer values.

If start is negative, it is treated as length + start where length is the length of the array. If end is negative, it is treated as length + end.

The copyWithin function is intentionally generic, it does not require that its this value be an Array object and in addition, copyWithin is a mutable method, it will change this object itself, and return it, not just return a copy of it.

Contributing

Pull requests and stars are always welcome.

For bugs and feature requests, please create an issue.

But before doing anything, please read the CONTRIBUTING guidelines.