function createEmptySpreadsheetData(rows, columns) {
  var data = [];
  var row;

  for (var i = 0; i < rows; i++) {
    row = [];

    for (var j = 0; j < columns; j++) {
      row.push('');
    }

    data.push(row);
  }

  return data;
}
Generates an empty data object.

@param {Number} rows Number of rows to generate.
@param {Number} columns Number of columns to generate
@returns {Array}