Array.prototype.toReversed()
Baseline 2023Newly available
Since July 2023, this feature works across the latest devices and browser versions. This feature might not work in older devices or browsers.
ThetoReversed() method ofArray instances is thecopying counterpart of thereverse() method. It returns a new array with the elements in reversed order.
Syntax
toReversed()Parameters
None.
Return value
A new array containing the elements in reversed order.
Description
ThetoReversed() method transposes the elements of the calling array object in reverse order and returns a new array.
When used onsparse arrays, thetoReversed() method iterates empty slots as if they have the valueundefined.
ThetoReversed() method isgeneric. It only expects thethis value to have alength property and integer-keyed properties.
Examples
Reversing the elements in an array
The following example creates an arrayitems, containing three elements, then creates a new array that's the reverse ofitems. Theitems array remains unchanged.
const items = [1, 2, 3];console.log(items); // [1, 2, 3]const reversedItems = items.toReversed();console.log(reversedItems); // [3, 2, 1]console.log(items); // [1, 2, 3]Using toReversed() on sparse arrays
The return value oftoReversed() is never sparse. Empty slots becomeundefined in the returned array.
console.log([1, , 3].toReversed()); // [3, undefined, 1]console.log([1, , 3, 4].toReversed()); // [4, 3, undefined, 1]Calling toReversed() on non-array objects
ThetoReversed() method reads thelength property ofthis. It then visits each property having an integer key betweenlength - 1 and0 in descending order, adding the value of the current property to the end of the array to be returned.
const arrayLike = { length: 3, unrelated: "foo", 2: 4,};console.log(Array.prototype.toReversed.call(arrayLike));// [4, undefined, undefined]// The '0' and '1' indices are not present so they become undefinedSpecifications
| Specification |
|---|
| ECMAScript® 2026 Language Specification # sec-array.prototype.toreversed |