SOURCE

function Add(a, b) {
  var sum = a ^ b;
  var carry = a & b;
  while (carry != 0) {
    a = sum;
    b = carry << 1;
    sum = a ^ b;
    carry = a & b;
  }

  return sum;
}

function oppositeNumber(n) {
  return Add(~n, 1);
}

function Minus(a, b) {
  return Add(a, oppositeNumber(b))
}

function Multiply(a, b) {
  if(a==1){
    return b;
  }
  var sum = 0;
  var index = 0;
  while(index<a){
    index = Add(index, 1);
    sum = Add(sum, b);
  }
  return sum;
}
function Add2(num1, num2) {  
    if(num2 == 0) return num1;//没有进位的时候完成运算  
    var sum, carry;  
    sum = num1 ^ num2;//完成第一步没有进位的加法运算 
    carry = (num1 & num2) << 1;//完成第二步进位并且左移运算  
    return Add2(sum,carry);//进行递归，相加  
}
console.log(Add2(56, 32));