Array.prototype.toReversed()

A new array containing the elements in reversed order.

The toReversed() method transposes the elements of the calling array object in reverse order and returns a new array.

When used on sparse arrays, the toReversed() method iterates empty slots as if they have the value undefined.

The toReversed() method is generic. It only expects the this value to have a length property and integer-keyed properties.

The following example creates an array items, containing three elements, then creates a new array that's the reverse of items. The items 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]

The return value of toReversed() is never sparse. Empty slots become undefined in the returned array.

console.log([1, , 3].toReversed()); // [3, undefined, 1]
console.log([1, , 3, 4].toReversed()); // [4, 3, undefined, 1]

The toReversed() method reads the length property of this. It then visits each index between length - 1 and 0 in descending order, and adds the value of that index in the original array to the corresponding index in the new array.

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 undefined

• Polyfill of Array.prototype.toReversed in core-js
• Array.prototype.reverse()
• Array.prototype.toSorted()
• Array.prototype.toSpliced()
• Array.prototype.with()
• TypedArray.prototype.toReversed()