A javascript code to get the excel cells array

Cell.js

var getCells = function (num) {
    var cellArray = [];
    for (var i = 0; i < num; ++i) {
        cellArray.push(cellAt(i + 1));
    }
    return cellArray;
};
var cellAt = function (num) {
    if (num <= 26) {
        return String.fromCharCode(97 + num - 1);
    } else {
        return cellAt(Math.ceil(num / 26) - 1) + cellAt(num % 26 || 26);
    }
};

console.log(getCells(704));