WFDASH-WEBAPP/.kilo/skills/vercel-react-best-practices/rules/js-tosorted-immutable.md
Dave 426bcb188a feat(duplicate-orders): refine duplicate order detection logic and UI enhancements
- Improved the `DuplicateOrdersDialog` component with better tab navigation for order number and line aggregate views.
- Enhanced the data structure for duplicate records to include `totalQuantity` and `totalSellingPrice` for more accurate detection.
- Implemented auto-flipping logic to ensure users see relevant content without encountering empty views.
- Expanded test coverage for the `findDuplicateOrders` function to validate new matching logic.
- Updated documentation to clarify duplicate identification criteria.
2026-08-16 16:27:45 +02:00

1.7 KiB

title impact impactDescription tags
Use toSorted() Instead of sort() for Immutability MEDIUM-HIGH prevents mutation bugs in React state javascript, arrays, immutability, react, state, mutation

Use toSorted() Instead of sort() for Immutability

.sort() mutates the array in place, which can cause bugs with React state and props. Use .toSorted() to create a new sorted array without mutation.

Incorrect (mutates original array):

function UserList({ users }: { users: User[] }) {
  // Mutates the users prop array!
  const sorted = useMemo(
    () => users.sort((a, b) => a.name.localeCompare(b.name)),
    [users]
  )
  return <div>{sorted.map(renderUser)}</div>
}

Correct (creates new array):

function UserList({ users }: { users: User[] }) {
  // Creates new sorted array, original unchanged
  const sorted = useMemo(
    () => users.toSorted((a, b) => a.name.localeCompare(b.name)),
    [users]
  )
  return <div>{sorted.map(renderUser)}</div>
}

Why this matters in React:

  1. Props/state mutations break React's immutability model - React expects props and state to be treated as read-only
  2. Causes stale closure bugs - Mutating arrays inside closures (callbacks, effects) can lead to unexpected behavior

Browser support (fallback for older browsers):

.toSorted() is available in all modern browsers (Chrome 110+, Safari 16+, Firefox 115+, Node.js 20+). For older environments, use spread operator:

// Fallback for older browsers
const sorted = [...items].sort((a, b) => a.value - b.value)

Other immutable array methods:

  • .toSorted() - immutable sort
  • .toReversed() - immutable reverse
  • .toSpliced() - immutable splice
  • .with() - immutable element replacement