tr elementthead element.tbody element.tfoot element.table element, after any
   caption, colgroup, and thead
   elements, but only if there are no tbody elements that
   are children of the table element.td or th elementsinterface HTMLTableRowElement : HTMLElement {
  readonly attribute long rowIndex;
  readonly attribute long sectionRowIndex;
  readonly attribute HTMLCollection cells;
  HTMLElement insertCell(optional long index);
  void deleteCell(long index);
};
   The tr element represents a row of cells in a table.
The tr element takes part in the table
  model.
rowIndexReturns the position of the row in the table's rows list.
Returns −1 if the element isn't in a table.
sectionRowIndexReturns the position of the row in the table section's rows list.
Returns −1 if the element isn't in a table section.
cellsReturns an HTMLCollection of the td and th elements of the row.
insertCell( [ index ] )Creates a td element, inserts it into the table
    row at the position given by the argument, and returns the
    td.
The position is relative to the cells in the row. The index −1, which is the default if the argument is omitted, is equivalent to inserting at the end of the row.
If the given position is less than −1 or greater than
    the number of cells, throws an IndexSizeError
    exception.
deleteCell(index)Removes the td or th element with the
    given position in the row.
The position is relative to the cells in the row. The index −1 is equivalent to deleting the last cell of the row.
If the given position is less than −1 or greater than
    the index of the last cell, or if there are no cells, throws an
    IndexSizeError exception.
The rowIndex
  attribute must, if the element has a parent table
  element, or a parent tbody, thead, or
  tfoot element and a grandparent
  table element, return the index of the tr
  element in that table element's rows collection. If there is no such
  table element, then the attribute must return
  −1.
The sectionRowIndex
  attribute must, if the element has a parent table,
  tbody, thead, or tfoot
  element, return the index of the tr element in the
  parent element's rows collection (for tables,
  that's the HTMLTableElement.rows
  collection; for table sections, that's the HTMLTableRowElement.rows
  collection). If there is no such parent element, then the attribute
  must return −1.
The cells attribute
  must return an HTMLCollection rooted at the
  tr element, whose filter matches only td
  and th elements that are children of the
  tr element.
The insertCell(index) method must act as follows:
If index is less than −1 or greater than the
  number of elements in the cells
  collection, the method must throw an IndexSizeError
  exception.
If index is missing, equal to −1, or
  equal to the number of items in cells collection, the method must create
  a td element, append it to the tr element,
  and return the newly created td element.
Otherwise, the method must create a td element,
  insert it as a child of the tr element, immediately
  before the indexth td or
  th element in the cells collection, and finally must
  return the newly created td element.
The deleteCell(index) method must remove the indexth element in the cells collection from its parent. If
  index is less than zero or greater than or equal
  to the number of elements in the cells collection, the method must
  instead throw an IndexSizeError exception.