Solution.js

/**
 * @param {character[][]} board
 * @return {boolean}
 */
var isValidSudoku = function (board) {
    const row = [...Array(9)].map(() => Array(9).fill(false));
    const col = [...Array(9)].map(() => Array(9).fill(false));
    const sub = [...Array(9)].map(() => Array(9).fill(false));
    for (let i = 0; i < 9; ++i) {
        for (let j = 0; j < 9; ++j) {
            const num = board[i][j].charCodeAt() - '1'.charCodeAt();
            if (num < 0 || num > 8) {
                continue;
            }
            const k = Math.floor(i / 3) * 3 + Math.floor(j / 3);
            if (row[i][num] || col[j][num] || sub[k][num]) {
                return false;
            }
            row[i][num] = true;
            col[j][num] = true;
            sub[k][num] = true;
        }
    }
    return true;
};