Use toSorted() Instead of sort() for Immutability

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