tesseract.js-core
Odds are you probably want to be using tesseract.js instead. It's a high level async API that works on the browser as well as the server. But if you're a big fan of manual memory management and slow, blocking computation, then you're at the right place!
The API essentially mirrors the Tesseract C++ API specified in baseapi.h. In particular, it's the subset which is described by tesseract.idl
Note that this didn't work for me on io.js v1.0.3 (giving a "read_params_file: parameter not found: enable_new_segsearch" error). Switching to Node v0.12.2 worked.