Theres also http://elasticlunr.com/, I'm not sure what algorithm it uses, but the site says "Elasticlunr.js use quite the same scoring mechanism as Elasticsearch, and also this scoring mechanism is used by lucene.", so maybe? I can't say I know that much about this topic...

I actually just used that library in creating a search for the docs site where I work and I have to say it works really well, it's a fully static site (hosted on github pages) and all the search is done in the browser based on an json "index" file that I generate along side the rest of the site. http://docs.exosite.com/