JSFiddle - React, Tailwind, and code Playground

JavaScript

function GetColumnFromIndex(index)
{
    var column = '';
    var columnNumber = index;
    while (columnNumber > 0)
    {
        var currentColumnNumber = (columnNumber - 1) % 26;
        var currentColumn = String.fromCharCode((currentColumnNumber + 65));
        column = currentColumn + column;
        columnNumber = (columnNumber - (currentColumnNumber + 1)) / 26;
    }
    return column;
}

function GetIndexFromColumn(column)
{
    var retVal = 0;
    var col = column.toUpperCase();
    for (var iChar = col.length - 1; iChar >= 0; iChar--)
    {
        var colPiece = col[iChar];
        var colNum = colPiece.charCodeAt(0) - 64;
        retVal = retVal + colNum * parseInt(Math.pow(26, col.length - (iChar + 1)));
    }
    return retVal;   
}
    
fr(var i = 0; i < 1000; i++)
   console.log(GetColumnFromIndex(i));

console.log(GetColumnFromIndex(22042293631005));
console.log(GetIndexFromColumn('DANISACOCK'));