Sudoku is a game played on a 9x9 grid. The goal of the game is to fill all cells of the grid with digits from 1 to 9, so that each column, each row, and each of the nine 3x3 sub-grids (also known as blocks) contain all of the digits from 1 to 9.

sudoku-resolve-function.js

/**
example:
validSolution([
  [5, 3, 4, 6, 7, 8, 9, 1, 2],
  [6, 7, 2, 1, 9, 5, 3, 4, 8],
  [1, 9, 8, 3, 4, 2, 5, 6, 7],
  [8, 5, 9, 7, 6, 1, 4, 2, 3],
  [4, 2, 6, 8, 5, 3, 7, 9, 1],
  [7, 1, 3, 9, 2, 4, 8, 5, 6],
  [9, 6, 1, 5, 3, 7, 2, 8, 4],
  [2, 8, 7, 4, 1, 9, 6, 3, 5],
  [3, 4, 5, 2, 8, 6, 1, 7, 9]
]); // => true
**/

function checkList(row) {
  let rowArr = row.filter((value, index, self) => {
    return self.indexOf(value) === index
  }).filter(v => v !== 0);
  
  return rowArr.length === 9 ? true : false
}

function blockArea(board) {
  let blockIsValid = false;
  let block = [];

  for(let a = 0; a < board.length; a+=3){
      for(let b = 0; b < board.length; b+=3){  
          block = [
              board[b][0+a], board[b][1+a], board[b][2+a],
              board[b+1][0+a], board[b+1][1+a], board[b+1][2+a],
              board[b+2][0+a], board[b+2][1+a], board[b+2][2+a]
          ];
  
          blockIsValid = checkList(block);
      }

      if(!blockIsValid) {
          break;
      }
  }
    
  return blockIsValid;
}

function rowNColumn(board) {
  let r = false;

  for(let a = 0; a < board.length; a++){
    let column = [];
    r = checkList(board[a])

    for(let b = 0; b < board.length; b++){
      column.push(board[b][a]);
    }
    r = checkList(column)
  }
  
  return r;
}

function validSolution(board){  
  let isSudokuValid = false;

  isSudokuValid = rowNColumn(board);
  
  if(isSudokuValid) {
    isSudokuValid = blockArea(board);
  }

  
  return isSudokuValid;
}