chessboard.js can't play a game with a set position

Question

When I use the example 'only allow legal moves http://chessboardjs.com/examples#5000, I can move the white and black pieces. When I want to set a fen string in the config, replacing position: 'start' by position: 'r1bqkbnr/pppp1ppp/2n5/1B2p3/4P3/5N2/PPPP1PPP/RNBQK2R', I can't move the pieces that have already been moved and if I move a piece that has never been moved, all the other pieces get back to the start position.

Any particular reason why you've tagged this question `php`? — Mark Baker, Sep 25 '14 at 08:02
About as relevant as saying you're running an nginx webserver, or that it's hosted in Indonesia.... chessboard.js doesn't care about any of that — Mark Baker, Sep 25 '14 at 12:53

Petr Chernyshev · Accepted Answer · 2015-04-05T23:02:33.407

'r1bqkbnr/pppp1ppp/2n5/1B2p3/4P3/5N2/PPPP1PPP/RNBQK2R' is not valid FEN format for chess.js because the library doesn't know about any parameters (move: black or white, castles, e.t.c).

var game = new Chess();
game.validate_fen('r1bqkbnr/pppp1ppp/2n5/1B2p3/4P3/5N2/PPPP1PPP/RNBQK2R');

//Object {valid: false, error_number: 1, error: "FEN string must contain six space-delimited fields."}

You should use correct FEN for chess.js. For example:

var game = new Chess("rnbqkbnr/pppp1ppp/8/4p3/4P3/8/PPPP1PPP/RNBQKBNR w KQkq e3 0 2");

// cfg.position == "rnbqkbnr/pppp1ppp/8/4p3/4P3/8/PPPP1PPP/RNBQKBNR w KQkq e3 0 2"

Or you can use game.load function. For example:

var game = new Chess();
game.load("rnbqkbnr/pppp1ppp/8/4p3/4P3/8/PPPP1PPP/RNBQKBNR w KQkq e3 0 2");

// cfg.position == "rnbqkbnr/pppp1ppp/8/4p3/4P3/8/PPPP1PPP/RNBQKBNR w KQkq e3 0 2"

So how can we convert `r1bqkbnr/pppp1ppp/2n5/1B2p3/4P3/5N2/PPPP1PPP/RNBQK2R` to valid chess.js fen? Coz we need that position of the board to start playing. — marukobotto, Jan 15 '19 at 13:10

score 0 · Answer 2 · answered Apr 03 '20 at 02:34

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If you look at your FEN string it isn't made up of 6 space delimited sections like the one below, which is valid. You only have the first bit in yours.

"rnbqkbnr/pppp1ppp/8/4p3/4P3/8/PPPP1PPP/RNBQKBNR w KQkq e3 0 2"

answered Apr 03 '20 at 02:34

omarjebari

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Amir · Answer 3 · 2022-04-08T00:27:22.940

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'r1bqkbnr/pppp1ppp/2n5/1B2p3/4P3/5N2/PPPP1PPP/RNBQK2R' this is only a part of FEN.

Example of valid FEN for chess.js:

"rnbqkbnr/pppp1ppp/8/4p3/4P3/8/PPPP1PPP/RNBQKBNR w KQkq - 0 2"

In the examples above, "-" is missing. It didn't work for me without it.

edited Apr 08 '22 at 00:27

answered Apr 08 '22 at 00:22

Amir

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chessboard.js can't play a game with a set position

3 Answers3