A way to attach multiple databases?

I can't figure out how to attach multiple databases to run queries across two sqlite files. Something like this:

ATTACH 'db1.sqlite3' AS db1;
ATTACH 'db2.sqlite3' AS db2;
SELECT * FROM db1.users NATURAL JOIN db2.meta

Works in sqlite at command line. Not sure how to achieve same effect here. Possible?

-Rob

No file or test is named in the issue; first inspect sql.js's database and query entry points and how SQLite files are loaded. Confirm whether multiple ATTACH statements can be supported, with completion demonstrated by querying across the two SQLite files.