Created
March 8, 2017 00:52
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Immutable move item in an array
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| /** | |
| * Immutable move item | |
| */ | |
| const move = (arr, from, to) => { | |
| const clone = [...arr]; | |
| Array.prototype.splice.call(clone, to, 0, | |
| Array.prototype.splice.call(clone, from, 1)[0] | |
| ); | |
| return clone; | |
| }; | |
| /** | |
| * Immutable move target a distance | |
| */ | |
| const moveTarget = (arr, target, distance) => { | |
| const from = arr.indexOf(target); | |
| if (~from) { | |
| return move(arr, from, from + distance); | |
| } | |
| }; | |
| describe('move', () => { | |
| it('can move', () => { | |
| const input = [1, 2, 3, 4, 5]; | |
| const expected = [1, 3, 4, 2, 5]; | |
| Object.freeze(input); | |
| Object.freeze(expected); | |
| const actual = move(input, 1, 3); | |
| expect(actual).toEqual(expected); | |
| }); | |
| it('can moveTarget', () => { | |
| const input = [1, 2, 9, 4, 5, 6, 7]; | |
| const expected = [1, 2, 4, 5, 9, 6, 7]; | |
| Object.freeze(input); | |
| Object.freeze(expected); | |
| const actual = moveTarget(input, 9, 2); | |
| expect(actual).toEqual(expected); | |
| }) | |
| }); |
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