Outer join of 2 tables in Bookshelf.js or Knex.js

I am new to Bookshelf.js and knex. I need to write a query equivalent to this in Bookshelf/ knex

SELECT Inv.*, Comp.* 
FROM  Inv,   Comp
WHERE Inv.uId =2 AND Comp.cId = Inv.cId;

Inv Table has:

Id     |  primary key, integer  not null
col1   | string data
cId    | integer, foreign key references C table
uId    | integer  foreign key reference U table      

Comp Table has:

cId     |  primary key, integer  not null 
col3    | string data