Implement numbering scheme like A,B,C... AA,AB,... AAA..., similar to converting a number to radix26 I want to implement numbering scheme like Microsoft Word uses for numbering. 
first one gets = A,next is  B, next is C, .... then AA, then AB,....and so on. 
as shown below

 A      
 B
 C
 . 
 .
 AA
 AB
 AC
 .
 .
 AAA
 AAB
 ....


'=>' here means converted to.

some examples:     

1 =&gt; A
26 =&gt; Z
27 =&gt; AA
52 =&gt; AZ
53 =&gt; BA


and heres the code for it:

   var convertToNumberingScheme = function(n){
        var x = n-1,
            r26 = x.toString(26),
            baseCharCode = "A".charCodeAt(0);

        var arr = r26.split(''),
            len = arr.length;

        var newArr =arr.map(function(val,i){
            val = parseInt(val,26);

            if( (i === 0) &amp;&amp; ( len &gt; 1)){
                val = val-1;
            }

            return String.fromCharCode(baseCharCode + val);
        });
        return newArr.join('');
    }


It seems to work fine, but any ideas if there are some potential bugs or ways to  optimize this.
The function in the question converts to base 26, then splits the resulting string, and converts each digit back to decimal - and then to a letter. That seems roundabout.

Here's a simpler one:

function convertToNumberingScheme(number) {
  var baseChar = ("A").charCodeAt(0),
      letters  = "";

  do {
    number -= 1;
    letters = String.fromCharCode(baseChar + (number % 26)) + letters;
    number = (number / 26) &gt;&gt; 0; // quick `floor`
  } while(number &gt; 0);

  return letters;
}


This function basically does a repeated "divmod" of the input number; getting the modulus 26 and the quotient (floor of n divided by 26). The modulus is converted to a A-Z character that's prepended to the output string, and the quotient is used as the input for the next iteration of the loop.