Soduku checker

soduku.js

// In this implementation it is assumed that grid is always 9x9
function sudoku2(grid) {
    // check rows
    for(let row = 0; row < grid.length; row++) {
        const numbersMap = new Set();
        for(let column = 0; column < grid[row].length; column++) {
            if(grid[row][column] === ".") continue;
            if (numbersMap.has(grid[row][column])) {
                return false;
            } else {
                numbersMap.add(grid[row][column]);
            }
        }
    }
    
    // check columns
    for(let column = 0; column < grid[0].length; column++) {
        const numbersMap = new Set();
        for(let row = 0; row < grid.length; row++) {
            if(grid[row][column] === ".") continue;
            if (numbersMap.has(grid[row][column])) {
                return false;
            } else {
                numbersMap.add(grid[row][column]);
            }
        }
    }
    
    // check each 3x3 grid
    for(let row = 0; row < grid.length; row += 3) {
        for(let column = 0; column < grid[row].length; column += 3) {
            const numbersMap = new Set();
            
            for(let i = row; i < row + 3; i++) {
                for(let j = column; j < column + 3; j++) {
                    if(grid[i][j] === ".") continue;
                    if (numbersMap.has(grid[i][j])) {
                        return false;
                    } else {
                        numbersMap.add(grid[i][j]);
                    }
                }
            }
        }
    }
    
    return true;
}