@jafayer/chessnut

Open ChessNut

An open source API for connecting to and interacting with the ChessNut Boards.

NOTE: Currently limited to USB connection only.

Usage

The API exposes connection logic both for server and web applications using the Web HID API.

First, import the connection logic for your app:

import {connect} from "@jafayer/chessnut/server";

or

import {connect} from "@jafayer/chessnut/web";

These functions optionally take a callback, or just return the HID reference synchronously. Most of the time, you'll want to immediately wrap the HID device in the ChessNut class:

import {ChessNut} from "@jafayer/chessnut";
const device = connect();
const chessnut = new ChessNut(device);
chessnut.listen();

Calling chessnut.listen begins the flow of board data. The data is pushed into an Rxjs BehaviorSubject. You can subscribe to the stream of board data by calling

chessnut.state.subscribe({next: callbackFn}).

This subscription will get a new value several times per second. You may want to limit the stream to only update when the value changes. To do this, install Rxjs as a codependency, and import the distinctUntilChanged operator to compare the previous state to the current state:

import {distinctUntilChanged} from "rxjs/operators";

chessnut.state
.pipe(distinctUntilChanged((prev, curr) => prev.toString() === curr.toString()))
.subscribe({
    next: (e) => console.log(e),
});

This will ensure the state only updates when the board state changes.

ChessNut API

.listen()

Puts the board into "realtime mode" and begins the flow of board data into the state observable.

state

An Rxjs BehaviorSubject containing the current board state. You can subscribe to the state (see Usage) to read board state live from the board.