How to prevent piece captures? about react-chessboard

[Epitomaniac]

So this statement makes sure the move has been a capture, right?
if (game.get(targetSquare) !== null)
I'll test it once I get back home, thanks for the reply and the wonderful library.

[Clariity]

export const Example = () => {
  const [game, setGame] = useState(new Chess());

  function onDrop(sourceSquare, targetSquare) {
    if (game.get(targetSquare) !== null) {
      return false;
    }
      
    const gameCopy = { ...game };
    const move = gameCopy.move({
      from: sourceSquare,
      to: targetSquare,
      promotion: "q", // always promote to a queen for example simplicity
    });
    setGame(gameCopy);

    // illegal move
    if (move === null) return false;
    return true;
  }

  return (
    <Chessboard
      id="PlayVsRandom"
      position={game.fen()}
      onPieceDrop={onDrop}
    />
  );
};

[Clariity]

I'm curious as to how you'd want this work? To overlay the pieces? A chess position cannot exist with multiple pieces on the same square

[Clariity]

if you just want to prevent a capture you can return false in onPieceDrop and the move will be disallowed

[Epitomaniac]

I'd like to test whether a user can set up the starting position correctly, I put the pieces randomly on the board and ask the user to set up the pieces; if the user puts a piece on top of another, the piece would be captured which is an unwanted result that breaks the app.

[Clariity]

what would you want to happen if a user puts a piece on top of another?

you could instead just return false in onPieceDrop if you don't want the move to happen

ultimately it's up to the react-chessboard user to pass the desired fen position to the board, so the logic can be programmed externally to the package to swap the pieces if desired

[Epitomaniac]

what would you want to happen if a user puts a piece on top of another?

I want the piece to snap back to where it was before the move was made, as if the move was illegal.

you could instead just return false in onPieceDrop if you don't want the move to happen

How do I check if the move was a capture?