// Set the data validation for cell A1 to require a value from B1:B10.
var cell = SpreadsheetApp.getActive().getRange('A1');
var range = SpreadsheetApp.getActive().getRange('B1:B10');
var rule = SpreadsheetApp.newDataValidation().requireValueInRange(range).build();
cell.setDataValidation(rule);
Builder for data validation rules.