toUpperCase

gistfile1.js

function numToChar(str) {
     var chartArr = str.split("");
     var chartLib = {
          a: 1,
          b: 2,
          c: 3,
          d: 4,
          e: 5,
          f: 6,
          g: 7,
          h: 8,
          i: 9,
          j: 10,
          k: 11,
          l: 12,
          m: 13,
          n: 14,
          o: 15,
          p: 16,
          q: 17,
          r: 18,
          s: 19,
          t: 20,
          u: 21,
          v: 22,
          w: 23,
          x: 24,
          y: 25,
          z: 26
     };
     var chartNumArr = chartArr.reverse().map(function(item) {
               return chartLib[item];
          }) //[23,23,10]
     var str = Math.max.apply(Math, chartNumArr) + 10;
     var num = 0;
     for (var i = 0, len = chartNumArr.length; i < len; i++) {
          num += (chartNumArr[i] + 9) * Math.pow(str, i);
     }
     console.log("(" + num + ")" + ".toString(" + str + ")");
     console.log((num).toString(str));
}

goood！i feel like this author is a fucking genius XD