findLast

Returns the last element for which the provided function returns a truthy value.

Use Array.prototype.filter() to remove elements for which fn returns falsy values, Array.prototype.pop() to get the last one.

const findLast = (arr, fn) => arr.filter(fn).pop();

findLast([1, 2, 3, 4], (n) => n % 2 === 1); // 3