code: function _findFocusCell($newTable, $startContainer) {
    const elementRowIndex = dataHandler.findElementRowIndex($startContainer);
    const elementColIndex = dataHandler.findElementColIndex($startContainer);
  
    return $newTable.find('tr').eq(elementRowIndex).find('td, th')[elementColIndex];
  }
docs: Find focus cell element like td or th.
  @param {jQuery} $newTable - changed table jQuery element
  @param {jQuery} $startContainer - start container jQuery element of text range
  @returns {HTMLElement}
  @private