JavaScript base conversion that provides up to 64 base conversion. Based on http://www.javascripter.net/faq/convert3.htm, read more: http://en.wikipedia.org/wiki/Radix

radix.js

/**
 * Examples:
 *   var R = Radix(2);
 *   R.to(10); will result in "1010"
 *   R.from("1010"); sill result in 10
 *   var R = Radix(16);
 *   R.to(10); will result in "a"
 *   R.from("a"); sill result in 10
 * 
 * Notice:
 *   Safe integer range to use: -9007199254740991 - 9007199254740991
 *   Read more: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/MAX_SAFE_INTEGER
 */

var Radix = function(Base) {
    var Chars = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ$~".substr(0, Base);
    var Convert = {
        to: function (Number) {
            var HexN = "", AbsInt = Math.floor(Math.abs(Number)), R;
            while (true) {
                R = AbsInt % Base;
                HexN = Chars.charAt(R) + HexN;
                AbsInt = (AbsInt - R) / Base;
                if (AbsInt == 0) {
                    break;
                }
            }
            return ((Number < 0) ? "-" + HexN : HexN);
        },
        from: function (String) {
            var Number = 0,
                String = String.toString(),
                Negative = String[0] == "-";
            for (var i = 0; i < String.length; i += 1) {
                if (Negative && !i) continue;
                Index = Chars.indexOf(String[i]);
                if (Index == -1) {
                    throw "Input error: The source string does not match the Base conversion.";
                }
                Number = Index + (Number * Base);
            }
            return Negative ? parseInt(Negative + Number) : Number;
        },
        encode: Convert.to,
        decode: Convert.from
    };

    return this.Convert;
};

Nice. What about fromRadix(key)?