N/file Module
File.id
Property Description: The internal ID of the file within the NetSuite File Cabinet. This value is automatically generated by NetSuite. This property is read-only.
Type: number
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.id

// Code Example 1

//Add additional code

//...

var fileObj = file.load({

    id: 'Images/myImageFile.jpg'

});

log.debug({

   details: "File ID: " + fileObj.id

    });

//...

//Add additional code



//SOURCE: https://system.netsuite.com/app/help/helpcenter.nl?fid=section_4229266178.html