Lozza

A UCI Javascript chess engine with NNUE evaluation. Try her here:-

https://op12no2.github.io/lozza-ui/play.htm

Lozza was primarily created for use in browsers, but can also be used with traditional chess UIs via Node - and because of that, on pretty-much any platform.

The code is best read using a folding editor. Start/end fold markers are /*{{{ fold name*/ and /*}}}*/.

Basic use in a browser

All you need is lozza.js from the latest lozzaN.zip release.

https://github.com/op12no2/lozza/releases

Here is a little example to do a 10 ply search:-

var lozza = new Worker('lozza.js');      

lozza.onmessage = function (e) {
  $('#dump').append(e.data);             // assuming jquery and a div called #dump
                                         // parse messages from here as required
};

lozza.postMessage('uci');                // lozza uses the uci communication protocol
lozza.postMessage('ucinewgame');         // reset tt
lozza.postMessage('position startpos');
lozza.postMessage('go depth 10');        // 10 ply search

Try this example here:-

https://op12no2.github.io/lozza-ui/ex.htm

More examples

A sister repo has more browser-based examples for playing and analysing etc. with Lozza.

https://github.com/op12no2/lozza-ui

You can try them here:-

https://op12no2.github.io/lozza-ui/play.htm

Play Lozza offline in chess user interfaces

Lozza can be used in popular chesss user interfaces like Banksia, Winboard, Arena and CuteChess via Node. Download the latest LozzaN.zip release and then follow the instructions in the wiki.

https://github.com/op12no2/lozza/releases

https://github.com/op12no2/lozza/wiki/Loading-Lozza-into-chess-user-interfaces

Acknowledgements

https://nodejs.org - Node

https://github.com/jw1912/bullet - bullet network trainer

https://www.chessprogramming.org/Main_Page - Chess programming wiki

https://computerchess.org.uk/ccrl/4040 - CCRL rating list

https://backscattering.de/chess/uci - UCI protocol

https://discord.gg/uM8J3x46 - Engine Programming Discord

https://talkchess.com - Talkchess forums

https://www.chessprogramming.org/Fruit - Early versions of Lozza used a HCE based on Fruit 2.1