Rule proposal: `prefer-change-array-by-copy`

“Change Array by copy” proposal

Fail

array.reverse();

array.sort();

const array = [...foo];
array.splice(0, 1);

const array = [...foo];
array[1] = 'changed';

Pass

array = array.withReversed();

array = array.withSorted();

const array = foo.withSpliced(0, 1);

const array = foo.withAt(1, 'changed');

[fisker]

The proposal has updated, see https://github.com/tc39/proposal-change-array-by-copy/commit/752e576db3d55e9d1d80a97df1f1e54c26ffbd7f

• withReversed -> toReversed
• withSorted -> toSorted
• withSpliced -> toSpliced
• withAt -> with

[fregante]

One pattern that I’ve been using is to clone arrays in the function parameters and I hope it can be preserved. I think the same thing applies to array destructuring.

Before

function foo(originalBar) {
	const bar = [...originalBar];
	return bar;
}

After

function foo([...bar] /* Shallow bar clone*/) {
	return bar;
}