for (var colIndex=0; colIndex < getRandomInt(minCols,maxCols); colIndex++) {
    for (var rowIndex=0; rowIndex < getRandomInt(minRows,maxRows); rowIndex++ ) {
        // add a class to this cell so that we know it needs to be an obstacle
        $("[data-row='"+rowIndex+"'][data-col='"+colIndex+"']").addClass("blue");
    }
}