js custom number base

toBaseX.js

// base 10 integer to custom any base string
var toBaseX = function (value, baseChars) {
  var result = "";
  var targetBase = baseChars.length;

  do {
    result = baseChars[value % targetBase] + result;
    value = Math.floor(value / targetBase);
  } while (value);

  return result;
};

// example base 66
toBaseX(66, "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz~-_.".split(""));  // "10"