for (var i = 0; i < array.length; i++) {
    if (newArray.indexOf(array[i]) === -1) {
      newArray.push(array[i]);
    }
  }

function greatestProduct(m) {
  var horizontal, vertical, diagonal;
  var greatProduct = 0;

  for (var i=0, nRows = m.length; i < nRows - 1; i++) {
    for (var j=0, nCols = m[0].length; j < nCols - 1; j++) {
      // 4 horizontal elements
      if (j < nCols-3) {
        horizontal = m[i][j] * m[i][j+1]   * m[i][j+2]   * m[i][j+3];
      }

      // 4 vertical elements
      if (i < nRows-3) {
        vertical   = m[i][j] * m[i+1][j]   * m[i+2][j]   * m[i+3][j];
      }

      // 4 Diagonal elements
      if (i < nRows-3 && j < nCols-3) {
        diagonal   = m[i][j] * m[i+1][j+1] * m[i+2][j+2] * m[i+3][j+3];
      }

      greatProduct = Math.max(greatProduct, horizontal, vertical, diagonal);
    }
  }

  return greatProduct;
}