Function copy

test/app/core/deltas.spec.js:25–25

      
  return describe('expandDelta', () => it('should not be confused by array index changes', function() {
    const copy = x => JSON.parse(JSON.stringify(x));
    const x = ([0, 1, 2, 3, 4, 5, 6, 7].map((y) => ({value: y, id: `ID:${y}`, squared: y*y})));
    x[3].target = 1;
    const x1 = copy(x);