Postgres-js is a project mainly written in JavaScript, it's free.
The postgres backend protocol implemented in pure JS for use with node.js
This library is a implementation of the PostgreSQL backend/frontend protocol in javascript. It uses the node.js tcp and event libraries. A javascript md5 library is included for servers that require md5 password hashing (this is default).
This is using the api from node-persistence and is used by sousaball.
See test.js for sample usage.