Convert numbers into any base e.g: 2, 8,16, 64,1024, 65500, etc.

baseN.js

/**
* Provides BaseN class
* 
* Encode and decode numbers as any base
*
* @example
*
*   var baseX = new BaseN() // Default base is 65,535
*   var sample = 9007199254740991
*   var encoded = baseX.encode(sample)
*   var decoded = baseX.decode(encoded)
*   console.log(sample)
*   console.log(encoded)
*   console.log(decoded)
*
* @module BaseN
*/
var BaseN = (function () {

/**
* @property DEFAULT_CHAR_MAP
* @type Array
*/
var DEFAULT_CHAR_MAP = []

for (var k = 0; k < 0xFFFF; k++) 
{
    DEFAULT_CHAR_MAP[DEFAULT_CHAR_MAP.length] = String.fromCharCode(k)
}

/**
* @class BaseN
* @constructor
*/
function BaseN(chars)
{
    if (typeof chars === 'number') 
    {
        if (chars > 1 && chars < 0x10000)
        {
            var size = chars 
            chars = []
            for (var k = 0; k < size; k++) 
            {
                chars[chars.length] = String.fromCharCode(k)
            }
        }
        else
        {
            throw new Error('Base size must be between 2 and 65535')
        }
    }

    if (typeof chars === 'string') 
    {
        chars = chars.split('')
    }

    if (Object.prototype.toString.call(chars) !== '[object Array]')
    {
        chars = DEFAULT_CHAR_MAP
    }

    this.base = chars.length
    this.chars = chars
    this.map = {}
    this.bits = 1

    while (this.base >> (this.bits + 1))
    {
        this.bits++;
    }

    for (var i = 0, len = chars.length; i < len; i++) 
    {
        this.map[ chars[i] ] = i
    }

}

/**
* @method encode
* @param number {Number}
* @return String
*/
BaseN.prototype.encode = function(number) 
{
    if (!number) return this.chars[0]
    
    var ret = ''

    while (number > 0) 
    {
        var rem = number % this.base
        number = Math.floor(number / this.base)
        ret = this.chars[rem] + ret
    }

    return ret
}

/**
* @method decode
* @param encoded {String}
* @return Number
*/
BaseN.prototype.decode = function(encoded) 
{
    var decoded = 0, multi = 1;
    for (var i = encoded.length - 1; i >= 0; i--) 
    {
        decoded += this.map[encoded.charAt(i)] * multi
        multi = multi * this.base
    }
    return decoded
}

return BaseN
})();