For now, mostly a PoC. Uses bitcore-node for transaction lookup and trezor-crypto for address derivation, compiled through emscripten and run in a web worker. Supports persisting discovered state and doing partial update later on. Should out-perform all wallets available today that do client-side chain discovery.
Example is in example/index.js; it is compiled in makefile to gh-pages directory by make example.
Built version is in gh-pages branch.
You can also try it yourself here - http://trezor.github.io/hd-wallet/example.html (note that xpubs are preloaded there, but some simple GUI for inputing the XPUBs could be probably done).
Running the tests require an installed regtest-bitcore and an empty regtest blockchain, but there is a docker that runs the bitcore in background.
Before running coverage, do
make bitcore-test-docker
And you can normally run coverage tests.
LGPLv3, (C) 2016 Karel Bilek, Jan Pochyla
Coinselect MIT, (C) 2015 Daniel Cousens