Javascript - Loop through array backwards with forEach

Question

Is there a way to loop backwards through an array using forEach (not any other kind of loop, I know how to do with with a for / standard ways) and without actually reversing the array itself?

Answer 1

let arr = [1, 2, 3];

arr.slice().reverse().forEach(x => console.log(x))

will print:

3
2
1

arr will still be [1, 2, 3], the .slice() creates a shallow copy.

Answer 2

There is a similar array method that has a reverse counter part, reduce comes together with reduceRight:

const array = ['alpha', 'beta', 'gamma'];

array.reduceRight((_, elem) => console.log(elem), null);

When using it for the requested purpose, make sure to provide a second argument. It can be null or anything else. Also note that the callback function has as first argument the accumulator, which you don't need for this purpose.

If including a library is an option:

Lodash: forEachRight.