Chai : Chai is a BDD / TDD assertion library for node and the browser that can be delightfully paired with any javascript testing framework.
SlimerJS : A scriptable browser for Web developers
PhantomJS : PhantomJS is a headless WebKit with JavaScript API. It has fast and native support for various web standards: DOM handling, CSS selector, JSON, Canvas...
LokiJS : A fast, in-memory document-oriented datastore for node.js, browser and cordova