Why does this work:

var fields = search.lookupFields({
	type: 'transaction',
	id: record_id,
	columns: fields
});

But this does not:

var fields = search.lookupFields({
	type: record.Type.TRANSACTION,
	id: record_id,
	columns: fields
});

?

you should use

search.Type

not

record.Type

may require you actually specify the type and not a generic "transaction" as it doesn't know what that is

It's def what stalbert said, record.Type.TRANSACTION is not a thing

Sandii has good point - and notable with TypeScript you'd get a compile time error on that.

TRANSACTION is listed as one of the available values under https://netsuite.custhelp.com/app/answers/detail/a_id/45161/kw/record.type

the point here is to use

search.Type

not

record.Type

regardless what what values are or are not available on record.Type, it's the wrong enumeration to use 🙂

^

yep yep.

In general, I don't look at the documentation for the record.Type or search.Type enumeration. I tend to just load

N/record

into chrome console and look through the list there.

similarly, in general I just let the TypeScript declaration drive it, since it autocompletes anyway.