JS calculation of the sum of two numbers __ algorithm

Question: Calculates the and of two digits.

Analysis: As we all know, number type of value has an upper limit, if it is two large numbers add sum, you cannot use the simplest + method, you can take two numbers as a string to deal with, starting from the end of the add, pay attention to the number of progressive digits, finally get the added string

Realize:

Arguments A, B are all string positive integers, sum
function Add (A, b) {
	var aLen = a.length,
		blen = b.length,
		maxlen = Alen-blen >= 0 ? Alen:blen,
		num = 0,		//Up-level recursive
		str = ';
	for (var i = 1; I <= maxlen i++) {
		var aval = alen-i >= 0 parseint (A.charat (alen-i)): 0,
			bval = Blen- I >= 0? parseint (B.charat (blen-i)): 0,
			bitval = 0,
			addval = aval + bval + num;
		if (Addval >=) {
			num = parseint (ADDVAL/10);
			Bitval = addval%;
		} else{
			num = 0;
			Bitval = Addval;
		}
		STR + + bitval;
	}
	return Array.prototype.reduceRight.call (str, function (A, b) {return a + B;});

The second way, recursive algorithm

function Add (A, b) {var Aarr = A.split ('). Reverse (), BARR = B.split ("). reverse (); Return (function Addstep (Aarr, BARR, str, num) {var aval = Aarr.length = 0? 0:parseint (Aarr.shift ()), Bval = BAr R.length = = 0? 0:parseint (Barr.shift ()), num = num | | 0, Bitval = 0, Addval = aval + bval + num, str = str | |
		'';
			if (addval >=) {num = parseint (ADDVAL/10);
		Bitval = addval% 10;
			}else{num = 0;
		Bitval = Addval;
		STR + + Bitval; if (Aarr.length = = 0 && barr.length = 0) {console.log (Array.prototype.reduceRight.call (str, function (A, b) {RE
		Turn A + b;});
		}else{Addstep (Aarr, BARR, str, num); }}) (Aarr, BARR, ', 0)}