Validate a sudoku board by passing this method the board numbers (left to right) in an array.

validate-sudoku.js

function validateSudoku(data) {
  // [] for rows/colums
  var board = [];
  // iterate over the (r)ows
  for (var r = 0; r < 9; r++) {
    // start for (c)olumns
    var start = r * 9;
    // stores current row data
    var build = [];
    // iterate over the (c)olumns
    for (var c = start; c < (start + 9); c++) {
      // add row data
      build.push(data[c]);
    }
    // insert row [] into board
    board.push(build);
  }
  // test board values
  var valid = true;
  // iterate over the (r)ows
  for (var r = 0; r < 9; r++) {
    // init row count
    var rowCheck = 0;
    // iterate over the (c)olumns
    for (var c = 0; c < 9; c++) {
      // cache current value
      var value = board[r][c];
      // init column count
      var columnCheck = 0;
      // add up column
      for (var x = 0; x < 9; x++) {
        columnCheck += board[x][c];
      }
      // add up row
      rowCheck += board[r][c]
      // test column
      if (columnCheck != 45) return false;
    }
    // test row
    if (rowCheck != 45) return false;
  }
  return true;
}

// examples (test1: false & test2: true)
var test1 = validate([9, 7, 6, 3, 1, 4, 2, 5, 8, 8, 5, 4, 9, 6, 2, 7, 1, 3, 9, 1, 3, 8, 7, 5, 2, 6, 4, 4, 6, 8, 1, 2, 7, 3, 9, 5, 5, 9, 7, 4, 3, 8, 6, 2, 1, 1, 3, 2, 5, 9, 6, 4, 8, 7, 3, 2, 5, 7, 8, 9, 1, 4, 6, 6, 4, 1, 2, 5, 3, 8, 7, 9, 7, 8, 9, 6, 4, 1, 5, 3, 2]);
var test2 = validate([2, 7, 6, 3, 1, 4, 9, 5, 8, 8, 5, 4, 9, 6, 2, 7, 1, 3, 9, 1, 3, 8, 7, 5, 2, 6, 4, 4, 6, 8, 1, 2, 7, 3, 9, 5, 5, 9, 7, 4, 3, 8, 6, 2, 1, 1, 3, 2, 5, 9, 6, 4, 8, 7, 3, 2, 5, 7, 8, 9, 1, 4, 6, 6, 4, 1, 2, 5, 3, 8, 7, 9, 7, 8, 9, 6, 4, 1, 5, 3, 2]);