function checkSheet() {
var sheetName = "Sheet1";
var folderID = "FOLDER_ID"; // Folder id to save in a folder.
var pdfName = "Invoice "+Date();

var sourceSpreadsheet = SpreadsheetApp.getActive();
var sourceSheet = sourceSpreadsheet.getSheetByName(sheetName);
var folder = DriveApp.getFolderById(folderID);

//Copy whole spreadsheet
var destSpreadsheet = SpreadsheetApp.open(DriveApp.getFileById(sourceSpreadsheet.getId()).makeCopy("tmp_convert_to_pdf", folder))

//delete redundant sheets
var sheets = destSpreadsheet.getSheets();
for (i = 0; i < sheets.length; i++) {
if (sheets[i].getSheetName() != sheetName){
destSpreadsheet.deleteSheet(sheets[i]);
}
}

var destSheet = destSpreadsheet.getSheets()[0];
//repace cell values with text (to avoid broken references) 
var sourceRange = sourceSheet.getRange(1,1,sourceSheet.getMaxRows(),sourceSheet.getMaxColumns());
var sourcevalues = sourceRange.getValues();
var destRange = destSheet.getRange(1, 1, destSheet.getMaxRows(), destSheet.getMaxColumns());
destRange.setValues(sourcevalues);

//save to pdf
var theBlob = destSpreadsheet.getBlob().getAs('application/pdf').setName(pdfName);
var newFile = folder.createFile(theBlob);

//Delete the temporary sheet
DriveApp.getFileById(destSpreadsheet.getId()).setTrashed(true);
}