With knexjs, how do I compare two columns in the .where() function?

As of knex 0.15.0 (July 2018), we now have:

table("table1").select().where("column1", "<", knex.ref("column2"))

See https://knexjs.org/#Ref

As Greg Hornby mentions in the comment to the other answer, you can also use ?? in a raw query to bind to a column or table name.

Ok, so after some digging, it looks like it can be done this way. Not sure if this is best practice, but at the moment, it works so until I hear otherwise...

.table("table1").select().where("column1", "<", knex.raw("table1.column2"))

Again, not ideal, but it gets the job done. Just be sure to

import knex from "knex";

at the top of whatever file you're using this in.