Note This proposal is 'finished' and has been merged into the ECMAScript spec. PR
Change Array by copy
Provides additional methods on
TypedArray.prototype to enable changes on the array by returning a new copy of it with the change.
This proposal is currently at Stage 4.
- Robin Ricard (Bloomberg)
- Ashley Claymore (Bloomberg)
This proposal introduces the following function properties to
Array.prototype.toReversed() -> Array
Array.prototype.toSorted(compareFn) -> Array
Array.prototype.toSpliced(start, deleteCount, ...items) -> Array
Array.prototype.with(index, value) -> Array
All of those methods keep the target Array untouched and returns a copy of it with the change performed instead.
with will also be added to TypedArrays:
TypedArray.prototype.toReversed() -> TypedArray
TypedArray.prototype.toSorted(compareFn) -> TypedArray
TypedArray.prototype.with(index, value) -> TypedArray
These methods will then be available on subclasses of
TypedArray. i.e. the following:
const sequence = [1, 2, 3]; sequence.toReversed(); // => [3, 2, 1] sequence; // => [1, 2, 3] const outOfOrder = new Uint8Array([3, 1, 2]); outOfOrder.toSorted(); // => Uint8Array [1, 2, 3] outOfOrder; // => Uint8Array [3, 1, 2] const correctionNeeded = [1, 1, 3]; correctionNeeded.with(1, 2); // => [1, 2, 3] correctionNeeded; // => [1, 1, 3]
Tuple.prototype introduces these functions as a way to deal with the immutable aspect of the Tuples in Record & Tuple. While Arrays are not immutable by nature, this style of programming can be beneficial to users dealing with frozen arrays for instance.
This proposal notably makes it easier to write code able to deal with Arrays and Tuples interchangeably.
Record & TupleRelationship with
While this proposal is derived from Record & Tuple, it should progress independently.
If web compatibility prescribes it, property names defined in this proposal are going to be changed. Those changes should be reflected on
Firefox/SpiderMonkey, currently flagged
Chrome/V8, shipping unflagged since Chrome 110
Ladybird/LibJS, shipping unflagged
./polyfill.js (minimalist reference implementation)