DriveApp createFile add undefined to file

Question

I want to create a file with google AppMaker using DriveApp. First i have created a String with the content of my file and then i use

var file = DriveApp.createFile("file.scl",content,MimeType.PLAIN_TEXT);

All content is generated like that

var content = "";
content = content + "First line \r\n";
content = content + "Second line \r\n";
content = content + "End";

The problem is when i open the created file the word "undefined" is added to the start of the first line. The content of the file:

undefinedFirst line
Second line
End

I have tried to remove the extension (.scl), replace with another extension, create a blob, change the MimeType, remove special char like "\r\n" but the "undefined" does not want to leave.

I d'ont know when and why this "undefined" is added to the file and i did not find any issue on the web.

Anyone have a suggestion ?

thanks.

Answer 1

I found the solution. My final content string is a concatenation of many string and one string was not initialized as a string. ( Yes, just that)

I have just add << = "" >> to make << var aString = "";>>