24-points javascript calculator unoptimized / no parenthesis removal / only single answer is shown

24-points-ver1.js

function wrap(num) {
	return ' ' + num + ' ';
}

function singleStep(ans, a, b, arr, i, target, sym) {
	arr[i] = ans;
	return (target = calc24(arr, target)) &&
		target.replace(wrap(ans), '(' + wrap(a) + sym + wrap(b) + ')');
}

function reduction(a, b, arr, i, target) {
	return singleStep(a + b, a, b, arr, i, target, '+') ||
		singleStep(a - b, a, b, arr, i, target, '-') ||
		singleStep(b - a, b, a, arr, i, target, '-') ||
		singleStep(a * b, a, b, arr, i, target, '*') ||
		singleStep(a / b, a, b, arr, i, target, '/') ||
		singleStep(b / a, b, a, arr, i, target, '/');
}

function calc24(arr, target) {
	if (arr.length == 1) {
		if (arr[0] == target)
			return wrap(arr[0]);
		else
			return null;
	}
	for (var i = 0; i < arr.length; i++) {
		var clone = arr.slice();
		clone.splice(i, 1);
		for (var j = i; j < clone.length; j++) {
			var result = reduction(arr[i], arr[j + 1], clone, j, target);
			clone[j] = arr[j+1];
			if (result) return result;
		}
	}
	return null;
}