StalinSort.js

function StalinSort(array) {
  if (!Array.isArray(array)) throw new TypeError('Argument must be an Array!');

  return array.reduce((prev, next) =>
    !prev.length ||
      next >= prev[prev.length - 1] ?
        [...prev, next] :
        prev
  , []);
}

module.exports = StalinSort

StalinSort.php

<?php

function StalinSort(array $xs): array
{
    if (count($xs) <= 1) {
        return $xs;
    }
    
    $zs = $xs;
    $x = array_shift($zs);
    $y = array_shift($zs);
    
    if ($x <= $y) {
        return [$x, ...sort([$y, ...$zs])];
    }
    
    return StalinSort([$x, ...$zs]);
}