Using iterative style to clone an object in JavaScript

Question

Is it possible to rewrite the following JavaScript recursive function to make it faster?

function clone_recursive(object) {
    var result = {};
    for (var key in object) {
        var value = object[key];
        if (typeof value === 'object') {
            result[key] = clone_recursive(value);
        } else {
            result[key] = value;
        }
    }
    return result;
}

I rewrote it in an iterative style but it doesn't gain any performance, in fact the speed dropped by ≈20%.

function clone_iterative(object) {
    var result = {};
    var queue = [{base: result, value: object}];
    var item;
    while (item = queue.shift()) {
        var current = item.value;
        var base = item.base;
        for (var key in current) {
            var value = current[key];
            if (typeof value === 'object') {
                var resultValue = base[key] = {};
                queue.push({base: resultValue, value: value});
            } else {
                base[key] = value;
            }
        }
    }
    return result;
}

http://jsperf.com/clone-an-object/13

Answer 1

It's doubtable that an iterative version would truly be faster, as you're replacing a recursive call with multiple calls to queueing functions. Where a transformation to iteration helps is in preventing stack overflows (as call stacks tend to be smaller than heaps in interpreted languages), and with tail-recursion in languages without tail-call optimization.