Expose API via useImperativeHandle.

[isofarro]

Following on from the suggestion in #14 , reimplemented my changes using a forwardRef and useImperativeHandle. Returns an instance of the Chessground API for the current board.

Sample code demonstrating it's use (added to the README too):

import{useEffect,useRef}from"react";importChessground,{Api,Config,Key}from"@react-chess/chessground";// these styles must be imported somewhereimport"chessground/assets/chessground.base.css";import"chessground/assets/chessground.brown.css";import"chessground/assets/chessground.cburnett.css";constCONFIG: Config={movable: {free: false},};// Demo game moves in long algebraic formconstMOVES=("e2e4 e7e5 g1f3 d7d6 d2d4 c8g4 d4e5 g4f3 d1f3 d6e5 "+"f1c4 g8f6 f3b3 d8e7 b1c3 c7c6 c1g5 b7b5 c3b5 c6b5 "+"c4b5 b8d7 e1c1 a8d8 d1d7 d8d7 h1d1 e7e6 b5d7 f6d7 "+"b3b8 d7b8 d1d8").split(" ");exportconstDemoGameMoves=()=>{constapiRef=useRef<Api|undefined>();useEffect(()=>{// Make a move every 2 secondsconstinterval=setInterval(()=>{constmove=MOVES.shift();if(move){apiRef.current!.move(move.substring(0,2)asKey,move.substring(2,4)asKey);}else{clearInterval(interval);}},2000);return()=>clearInterval(interval);});return(<Chessgroundwidth={640}height={640}config={CONFIG}ref={apiRef}/>);};

[nowszy94]

Would be nice to have api usage example in README.md

[nowszy94]

What about exposing the whole chessground api instead of creating custom object?

[isofarro]

Sure, we can do that. Done now.

Also re-exported Config, Api and Key from the chessground API to reduce the clutter of imports in code using this React wrapper. Does that sound sensible?

[isofarro]

Would be nice to have api usage example in README.md

I've added the example demo-game component from this PR description to the README, and added ref to the props documentation.

[nowszy94]

i really like this example!

[nowszy94]

lets remove it

[isofarro]

Removed.

[nowszy94]

is it needed? It looks like it can only be fired after line 34 completes and after that the config is already provided

[isofarro]

I gave it a quick test, and you're right, it doesn't look to be needed. Removed.

[nowszy94]

Looks fantastic!