N/file Module
File.fileType
Property Description: The file type of a file. This property is read-only. You must set the file type by passing in a file.Type enum value to file.create(options).
Type: enum
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.fileType

// Code Example 1

//Add additional code

//...

var fileObj = file.load({

    id: 145

});

log.debug({

    details: "File Type: " + fileObj.fileType

    });

//...



//Add additional code



//SOURCE: https://system.netsuite.com/app/help/helpcenter.nl?fid=section_4229267378.html