Nodejs Utililty Methods Number to Base Convert

"use strict";
Number.prototype.toBase = function (base) {
    var symbols = 
    "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ".split("");
    var decimal = this;
    var conversion = "";
    if (base > symbols.length || base <= 1) {
        return false;
    while (decimal >= 1) {
        conversion = symbols[(decimal - (base * Math.floor(decimal / base)))] + 
                     conversion;
        decimal = Math.floor(decimal / base);
    return (base < 11) ? parseInt(conversion) : conversion;

Number.prototype.toBijectiveBase26 = (function () {
  return function toBijectiveBase26() {
    n = this
    ret = "";
    while(parseInt(n)>0){
      --n;
      ret += String.fromCharCode("A".charCodeAt(0)+(n%26));
      n/=26;
    return ret.split("").reverse().join("");
  };
}());

Number.prototype.define("base", function(b, c) {
  var s = "", n = this
  if (b > (c = (c || "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz").split("")).length || b < 2) {
    return ""
  while (n) {
    s = c[n % b] + s, n = Math.floor(n / b)
  return s
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