function mergeCellsExample() {

  //We can use an array of arrays to populate our table.

  var cells = [

    ['First cell', 'Second cell'],

    ['First cell second row', 'Second cell second row']

  ];

​

  //Creates an example document in your Google Drive Root Folder.

  //It will be titled "Cell merge example"

  var table = DocumentApp.create('Cell merge example').getBody().appendTable(cells);

​

  // Get the first row in the table.

  var row = table.getRow(0);

​

  // Get the two cells this row.

  var cell1 = row.getCell(0);

  var cell2 = row.getCell(1);

​

  // Check the contents of cells 1 and 2

  Logger.log('Cell1 contents: %s', cell1.getText());

  Logger.log('Cell2 contents: %s', cell2.getText());

​

  // TableCell.merge() merges the current cell into its preceding sibling element.

  var merged = cell2.merge();  

  Logger.log('Merged cell contents: %s', merged.getText());

​

  // Cell1 and merged are the same cell

  Logger.log('Cell1 == Merged cell: %s', cell1.getText() == merged.getText());

  // Cell2 no longer exists

  Logger.log('Cell2 contents: %s', cell2.getText());

}

​