Simple grid creator...

simple_grid_creator.js

var createGrid = function (rows, cols) {
    var str = "",
        odd = "o",
        even = "#";
    for (var row = 0; row < rows; row++) {
        for (var col = 0; col < cols; col++) {
            if ((row + col) % 2 === 0) {
                str += even;
            } else {
                str += odd;
            }
        }
        str = "";
    }
};

createGrid(8, 8);