Quicksort: comparison of recursive and loop

quick_sort.js

var swap = function(elements, i, j) {
    var temp = elements[i];
    elements[i] = elements[j];
    elements[j] = temp;
};

var calculate_pivot_index = function(elements, left, right) {
    return right;
};

var partition = function(elements, left, right) {
    swap(elements, right, calculate_pivot_index(elements, left, right));
    var pivot = elements[right];
    var leftEnd = left - 1;
    for (var i = left; i < right; i++) {
        if (elements[i] <= pivot) {
            leftEnd++;
            swap(elements, leftEnd, i);
        }
    }
    var middle = leftEnd + 1;
    swap(elements, middle, right);
    return middle;
};

// 再帰版
var quick_sort_recursive = function(elements) {
    var quick = function(elements, left, right) {
        if (right - left > 1) {
            var middle = partition(elements, left, right);
            quick(elements, left, middle - 1);
            quick(elements, middle + 1, right);
        }
    };
    quick(elements, 0, elements.length - 1);
};


// ループ版
var quick_sort_loop = function(elements) {
    var stack = [];
    stack.push({left: 0, right: elements.length - 1});

    while (true) {
        if (stack.length > 0) {
            var context = stack.pop();
            if (context.right - context.left > 1) {
                var middle = partition(elements, context.left, context.right);
                stack.push({left: context.left, right: middle - 1});
                stack.push({left: middle + 1, right: context.right});
            }
        } else
            break;
    }
};

(function() {
    var e = [2, 1, 0, 7, 6, 5, 9];
    quick_sort_recursive(e);
    console.log(e);

    var f = [2, 1, 0, 7, 6, 5, 9];
    quick_sort_loop(f);
    console.log(f);
})();