N/file Module
File.encoding
Property Description: The character encoding on a file. Value is set with the file.Encoding enum.
Type: string
Supported Script Types: Server-side scripts For more information, see SuiteScript 2.0 Script Types.
Module: N/file Module
Since: 2015.2
Search NetSuite - https://system.netsuite.com/app/help/helpcenter.nl?search=File.encoding

// Code Example 1

//Add additional code

//...

var fileObj = file.create({

    name    : 'test.txt',

    fileType: file.Type.PLAINTEXT,

    contents: 'Hello World\nHello World'

    });

fileObj.encoding = file.Encoding.MAC_ROMAN;

fileObj.folder = 30;

var fileId = fileObj.save();

//...



//Add additional code



//SOURCE: https://system.netsuite.com/app/help/helpcenter.nl?fid=section_4229270853.html