Christian Heilmann

New array methods in JavaScript bring immutability

Tuesday, June 6th, 2023 at 3:57 pm

Scarlet Witch saying no more mutants

JavaScript now has a way to change elements, sort, reverse and splice arrays without changing the original, thus giving it immutability. Four new methods allow you to change arrays without having to create a copy first. The new methods are `with()`, `toSorted()`, `toReversed()` and `toSpliced()`. No need to create a copy with `[...arr]` first. Only missing support in terms of browsers is Firefox.

const arr = ['f','c','k','a','f','d'];
const newArr = arr.with(2,'m');
// newArr -> ['f', 'c', 'm', 'a', 'f', 'd']
const sortArr = arr.toSorted();
// sortArr -> ['a', 'c', 'd', 'f', 'f', 'k']
const reverseArr = arr.toReversed();
// reverseArr -> ['d', 'f', 'a', 'k', 'c', 'f']
const splicedArr = arr.toSpliced(3, 3, 'it');
// splicedArr -> ['f', 'c', 'k', 'it']

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