Positional Notation Encoder/Decoder

baseConvert.js

var BASE02 = "01"; //Binary
var BASE04 = "0123";
var BASE08 = "01234567"; //Octal
var BASE10 = "0123456789"; //Decimal
var BASE16 = "0123456789ABCDEF"; //Hexadecimal
var BASE36 = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
var BASE62 = "abcdefghijklmnopqrstuvwxyz0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
var BASE75 = "abcdefghijklmnopqrstuvwxyz0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ_.,!=-*(){}[]"; //URL SAFE

function getValueOfDigit(digit, alphabet)
{
	var pos = alphabet.indexOf(digit);
	return pos;
}

function convert(src, srcAlphabet, dstAlphabet)
{
	var srcBase = srcAlphabet.length;
	var dstBase = dstAlphabet.length;

	var work = src;
	var val = 0;
	var multiple = 1;

	while (work.length > 0)
	{
		var digit = work.charAt(work.length - 1);
		val += multiple * getValueOfDigit(digit, srcAlphabet);
		work = work.substring(0, work.length - 1);
		multiple *= srcBase;
	}

	work = val;
	var output = "";

	while (work >= dstBase)
	{
		var digitVal = work % dstBase;
		var digit = dstAlphabet.charAt(digitVal);
		output = digit + output;
		work /= dstBase;
	}

	var digit = dstAlphabet.charAt(work);
	output = digit + output;

	return output;
}

var encoded = convert("1234567890",BASE10,BASE62); //Output: bv8h5u
var decoded = convert(encoded,BASE62,BASE10);      //Output: 1234567890