https://www.pbainbridge.co.uk/2019/02/save-email-to-drive-add-on-get-student.html

Save email to Drive add-on - get student details.gs

function getDetails(userId) {
  
  //get spreadsheet data from Global variable in 'spreadsheetID.gs'
  var ss = SpreadsheetApp.openById(ssId);
  var dataSheet = ss.getSheetByName('data');
  var list = dataSheet.getDataRange().getValues();
  
  //reset variables for loop
  var folderId = ''; 
  var forename='';
  var surname='';
  var detailsError = 0;
  
  //convert data array to string so can use 'indexOf'
  var listString = list.toString();
  //Logger.log(string);
  
  //look for userId string in data array - to determine if the below 'loop' should run
  var username = listString.indexOf(userId);
  Logger.log('Username indexOf is: ' + username);
  
  //check userId exists on spreadsheet, from indexOf, before proceeding
  if (username > -1) {
    
    Logger.log('Username exists in spreadsheet, proceeding to get Folder ID + Name');
    
    //length of array to loop through below
    var l = list.length;
    
    //loop through to lookup username match and then get Folder ID + Name *****************************************
    for (var i=1; i<l; i++) {
      
      if (list[i][0] == userId) {
        
        //from Col B/C
        if (list[i][1] != '') {
          forename = list[i][1];
          surname = list[i][2];
          Logger.log(forename + ' ' + surname + ' matches ' + userId);
        }
        else {
          //error increase by 2 for missing name
          detailsError+=2;
        }
        
        //from Col D
        if (list[i][3] != '') {
          folderId = list[i][3];
          Logger.log('Folder ID is: ' + folderId);
        }
        else {
          //error increase by 3 for missing folder ID
          detailsError+=3;
        }
        
      }
      
    }//end of loop through to lookup username match and then get Folder ID + Name *********************************
    
  }//end of check userId exists on spreadsheet, from indexOf, before proceeding
  else { 
    //else userId not exist on spreadsheet. Error increase by 1 for missing userId
    detailsError++;
  }
  
  //return as array so can extract each part as required
  return [[forename], [surname], [folderId], [detailsError]];
  
}