Xnary (like binary but different) counting

Question

I\'m making a function that converts a number into a string with predefined characters. Original, I know. I started it, because it seemed fun at the time. To do on my own. W

Answer 1

In the lengthy answer by @Daniel I see a call to log() which is a red flag for performance. Here is a simple way without much complex math:

function excelize(colNum) {
    var order = 0, sub = 0, divTmp = colNum;
    do {
        divTmp -= 26**order;
        sub += 26**order;
        divTmp = (divTmp - (divTmp % 26)) / 26;
        order++;
    } while(divTmp > 0);

    var symbols = "0123456789abcdefghijklmnopqrstuvwxyz";
    var tr = c => symbols[symbols.indexOf(c)+10];
    Number(colNum-sub).toString(26).split('').map(c=>tr(c)).join('');
}

Explanation:

Since this is not base26, we need to substract the base times order for each additional symbol ("digit"). So first we count the order of the resulting number, and at the same time count the substract. And then we convert it to base 26 and substract that, and then shift the symbols to A-Z instead of 0-P.