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:
- Props/state mutations break React's immutability model - React expects props and state to be treated as read-only
- 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