javascript通过位运算完成两个数的交换

<script type="text/javascript">//位运算法function swap(a,b) {    a = a^b;    b = a^b;    a = a^b;    return [a,b];}alert(swap(5,9));//加减法function swap(a,b) {    a = a-b;    b = a+b;    a = b-a;    return [a,b];}alert(swap(3,4));</script>