JavaScript でテーブルの行とセルを反復処理する方法

var table = document.getElementById("mytab1");

for (var i = 0, row; row = table.rows[i]; i++) {
  // 'row' represents the current row being iterated
  // Access data and manipulate as needed
}

  for (var j = 0, col; col = row.cells[j]; j++) {
    // 'col' represents the current cell being iterated
    // Access data and manipulate as needed
  }

for (var i = 0, cell; cell = table.cells[i]; i++) {
  // 'cell' represents the current cell being iterated
  // Access data and manipulate as needed
}