export_from_google_spreadsheet_to_drive_csv.gs

/*
 * script to export data in all sheets in the current spreadsheet as individual csv files
 * files will be named according to the name of the sheet, original content will be overwritten
 * author: Lucas Santos from Michael Derazon's code
*/
function onOpen() {
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  var csvMenuEntries = [{name: "export as csv files", functionName: "saveAsCSV"}];
  ss.addMenu("csv", csvMenuEntries);
};

function saveAsCSV() {
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  var sheets = ss.getSheets();
  // create a folder from the name of the spreadsheet
  var name = ss.getName().toLowerCase().replace(/ /g,'_') + '-csv';
  var folder = DriveApp.getFoldersByName(name).hasNext() ? DriveApp.getFoldersByName(name).next() : null;
  if(!folder) {
      folder = DriveApp.createFolder(name);
  } 
  for (var i = 0 ; i < sheets.length ; i++) {
    var sheet = sheets[i];
    // append ".csv" extension to the sheet name
    var fileName = sheet.getName() + ".csv";
    // convert all available sheet data to csv format
    var csvFile = convertRangeToCsvFile_(fileName, sheet);
    // create a file in the Docs List with the given name and the csv data
    var file = folder.getFilesByName(fileName).hasNext() ? folder.getFilesByName(fileName).next() : null;
    if(!file) {
      file = folder.createFile(fileName, csvFile);
      Browser.msgBox(i+' of '+sheets.length+' File created ' + file.getName());
    } else {
      file.setContent(csvFile);
      Browser.msgBox(i+' of '+sheets.length+' File updated ' + file.getName());
    }
  }  
}

function convertRangeToCsvFile_(csvFileName, sheet) {
  // get available data range in the spreadsheet
  var activeRange = sheet.getDataRange();
  try {
    var data = activeRange.getValues();
    var csvFile = undefined;

    // loop through the data in the range and build a string with the csv data
    if (data.length > 1) {
      var csv = "";
      for (var row = 0; row < data.length; row++) {
        for (var col = 0; col < data[row].length; col++) {
          if (data[row][col].toString().indexOf(",") != -1) {
            data[row][col] = "\"" + data[row][col] + "\"";
          }
        }

        // join each row's columns
        // add a carriage return to end of each row, except for the last one
        if (row < data.length-1) {
          csv += data[row].join(",") + "\r\n";
        }
        else {
          csv += data[row];
        }
      }
      csvFile = csv;
    }
    return csvFile;
  }
  catch(err) {
    Logger.log(err);
    Browser.msgBox(err);
  }
}