Jinja-like JS templating language
Have a look at Nunjucks, a JS templating engine heavily inspired by Jinja2. It supports block inheritance, macros, filters and much more and works both server (NodeJS) and client-side (most browsers).
My JavaScript Jinja implementation can be found here:https://github.com/sstur/jinja
It supports both Jinja and Liquid syntax, runs on the browser and in Node, will compile templates to dependency-free JavaScript, and is about 3K gzipped
Tests included. Express.js support in progress..
Link from @pradeek's comment. It is a port of jinja to js.