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<title> bzChess example - Viewing PGN </title>
<meta name="author" content="Gábor Martini" />
<meta name="keywords" content="chess fen pgn puzzle" />
<meta name="description" content="Javascript chess object to display positions" />
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<SCRIPT type="text/javascript" LANGUAGE=javascript src="bzchess.js"></script>
<LINK rel="stylesheet" type="text/css" media="screen" href="chess.css" />
<script type="text/javascript">
<!--
function bza_init_chesstable(el) {
el.chessgame = new bzChess(el);
el.chessgame.onDraw=function(){
comment.innerHTML = this.mv.comment;
}
el.chessgame.onAfterLoadPGN=function(lr){
this.mv=this.getfirst();
this.drawPieces();
alert("PGN loaded");
comment.innerHTML = this.mv.ravtitle;
}
}
//-->
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<body onload="bza_init_chesstable(mybrd)">
<h1>Example: Viewing PGN - Portable Game Notation</h1>
<p style="margin: 0px;">The PGN string must put to the text box or you can use the predefined one. With the "Load PGN" button the board will load all moves and move variation.</p>
<p style="margin: 0px;">The stepps can displayed width the "Next move" or "Prev move" buttons. If the next stepp has more variation an input dialog will be displayed. The nubers represents the variations.</p>
<table width="100%">
<tr>
<td style="vertical-align: top;">
<p>Move comment:</p>
<div id="comment" style="border: 1px solid green; height:40px; width: 500px; margin-bottom: 10px; overflow: auto;"></div>
<div id="mytbl" class="chtbl"><div id="mybrd" class="chbrd" bzaobj="chesstable"></div></div>
<div style="border: 1px solid transparent; width: 500px; margin-top: 10px; text-align:center;">
<input type="button" title="Prev move" value="<<< Prev move" onclick="mybrd.chessgame.prev()" />
<input type="button" value="Next move >>>" title="Next move" onclick="mybrd.chessgame.next()" /><br />
</div>
</td>
<td style="vertical-align: top;"><br />
<div style="border: 1px solid green; width: 600px; margin-bottom: 10px;">
<textarea id="pgnsample" rows="20" cols="80" style="font-size: 8pt;">
[Event "Sparkassen Gp 1"]
[Site "Dortmund GER"]
[Date "2002.07.11"]
[Round "6"]
[White "Shirov, Alexei"]
[Black "Gelfand, Boris"]
[Result "1-0"]
[ECO "B51"]
[WhiteElo "2697"]
[BlackElo "2710"]
[EventDate "2002.07.06"]
[Annotator "Hathaway, Mark"]
1. e4 c5 { Gelfand plays openings which are ideal for an aggressive player, but he isn't a wild-eyed tactician; he's a planner and classical positional player. } 2. Nf3 Nc6 3. Bb5 d6 ( 3...Qc7 ) ( 3...g6 ) 4. Bxc6+ bxc6 ; line end comment
5. O-O Bg4 ( 5...e5 { Kasparov-Polgar, Eurotel, 2002, 1-0 } ) 6. h3 Bh5 7. e5 { White's aim is to open the e-file or to "break" Black's pawn structure. The immediate threat of e5-e6 is reminiscent of an Alekhine's Defense position. If White doesn't play e4-e5 immediately then Black might get sufficient control of e5 to keep White boxed-in on the light squares. } 7...e6 { Black tries to keep control of e5 to prevent White from playing g2-g4 followed by Nf3-e5. } ( 7...d5 8. e6 fxe6 9. Re1 ) ( 7...dxe5 $5 8. g4 ( 8. Re1 $6 f6 ( 8...Qd5 $6 9. g4 Bg6 10. Rxe5 Qd6 ) ) 8...Bg6 9. Nxe5 Qd6 { and it's not clear who's weaknesses are most significant } ) 8. exd6 Bxd6 { While Black gets good piece activity the poor pawn structure must make Gelfand a little nervous. } 9. d3 ( 9. d4 cxd4 10. Qxd4 Bxf3 ( 10...Bh2+ $4 11. Kxh2 Bxf3 12. Qxg7 Qf6 13. Qxf6 Nxf6 14. gxf3 ) 11. Qxg7 Qf6 12. Qxf6 Nxf6 13. gxf3 Rg8+ 14. Kh1 Rb8 { and Black's terrific piece activity should give him the advantage. The immediate threat of ...Rb8-b5-h5xh3# should make White worry. } ) 9...Ne7 10. Nbd2 O-O { Playing a Nh4 or Nd4 to add pressure to the pin on Nf3 would be desirable, but White can step out of the pin with Qd1-e1. Black has to do more, so he castles and prepares to bring more forces into play. } ( 10...Nf5 { is a very uncertain sacrifice offer } 11. Qe1 ( 11. g4 Bg6 12. gxf5 Bxf5 13. Kg2 ) 11...O-O ( 11...Nd4 12. Nxd4 cxd4 13. Qe4 Rc8 { leaves Bh5 striking at thin air and Pd4 is a little weak } ) 12. g4 Bg6 13. gxf5 Bxf5 14. Kg2 ) 11. Ne4 { Though White needs to clear the way for Bc1 to develop it's a little odd to see him weaken Nf3 this way. Does he intend to move Bc1 and then play Ne4-d2 to re-establish the defense of Nf3, or is g2-g4 still being considered? } 11...Nd5 12. Re1 { White's pawn structure is quite modest, but from that his pieces might spring forward. Only the pin on Nf3 is troublesome. } 12...Re8 { It appears Black might want to play ...e6-e5 to secure control of d4 and f4, but he might also have in mind to play ...Bd6-f8 to keep the bishop on the board. } ( 12...Rb8 ) 13. Ng3 { So, this is the idea behind Nd2-e4. Black has to either retreat and give up on the pin on Nf3 or give up one of the bishops for a knight. He could trade off Bd6 (13...Bxg3 14. fxg3) or Bh5 (13...Bxf3 14. Qxf3) . } 13...Bg6 { Apparently he didn't see any immediate value to trading, so he keeps the two bishops in hopes of some future time when they'll be especially valuable. } 14. Ne4 Bc7 $2 { I don't understand giving up Pc5 in this situation. What plan does Black follow which demands the bishop be at c7 rather than d6 or f8? } ( 14...Bxe4 $6 15. dxe4 Nb6 16. e5 Bf8 17. Qe2 { and Black is cramped on the king-side by Pe5 and his queen-side is awkward } ) 15. Nxc5 e5 { Black threatens to open the position, possibly with ...f7-f5, ...e5-e4, before White can complete his development. } 16. a3 { White, apparently, is not terribly impressed and simply uses Pa3 to oppose Nd5 and possibly to support b2-b4, whereby Nc5 is defended and Bc1-b2 becomes available. } 16...f5 17. c4 { The resulting weakness at d4 seems trivial. The more important thing is to get rid of Nd5, so Bc1 can be developed to a useful square. } 17...Nf6 18. d4 $5 ( 18. Bg5 ) 18...e4 19. Ne5 ( 19. Nh4 Bh5 20. Qa4 Qd6 21. g3 { when Nh4 is a bit stranded, but Bh5 isn't necessarily very good and Pd4 is weak, but Pc6 is too. There are a lot of positional features which have to be comprehended before it can be said who is better or what their plans are. } ) 19...Bh5 ( 19...Bxe5 20. dxe5 Rxe5 { seems simple enough and a good choice for Black. White is simply giving back the pawn he'd won earlier, to ensure easy development and a queen-side pawn majority for the ending. } 21. b4 { secures Nc5 and prepares either Bc1-b2 or Bc1-f4 } ( { not bad, but perhaps not best is } 21. Be3 Bh5 22. Qa4 Qd6 23. b4 Ree8 { when Black threatens ...f5-f4 } ) 21...Bh5 22. Qa4 Qe8 23. Bf4 Re7 24. Bd6 Rf7 ) 20. Qd2 { just keeping Pd4 defended, however awkward it may be } 20...Qd6 { This clearly indicates he intends to get rid of Ne5 with his rook, hoping to retain control of f4 with Qd6 & Bc7. } 21. Qc3 Rad8 ( 21...Rxe5 $4 22. dxe5 Qxc5 23. exf6 ) 22. Be3 { Black has reached an impasse. His queen and rooks and even Bc7 are blocked severely on dark squares by Pd4 & Ne5. } 22...Rxe5 ( 22...f4 $4 23. Bxf4 Qxd4 24. Qxd4 Rxd4 25. Nxc6 ) 23. Nb7 { White keeps Pd4 and Be3 to maintain control of the central dark squares. } ( 23. dxe5 Qxe5 24. Qxe5 Bxe5 25. Rab1 f4 26. Bc1 { and Black has some advantages which compensate for the exchange sacrifice } 26...Bg6 ) 23...Qf8 24. dxe5 { White wins one exchange and now threatens two more! This looks like a catastrophe for Black. } ( 24. Nxd8 Re8 25. Nxc6 f4 ) 24...Rd3 { saving one exchange and gaining time to save the other } 25. Qb4 Bxe5 26. Qxf8+ Kxf8 { At this moment it appears Black has made the necessary breakthrough. Be5 is a powerhouse and Rd3 is also very good. } 27. Nc5 Rd6 28. Nb7 Rd7 29. Nc5 { White seems satisfied to repeat the position. Black may think he has the better of it, so he tries for more. I don't think that's a wise decision. } 29...Re7 30. Rab1 f4 31. Bd2 { This move is what Black allowed when he refused to repeat the position and played 29...Re7. White now threatens Nc5xe4. } 31...Bd6 ( 31...Bd4 32. Bb4 Kf7 33. Nb3 Rd7 34. Nxd4 Rxd4 35. Bc5 Rxc4 36. Bxa7 { and the fight goes on, but Black no longer has the advantage of the two bishops! } ) 32. b4 ( 32. Bb4 $4 a5 ) 32...Kf7 $6 ( { It might be too late for Black to turn back the tide, because of the earlier exchange sacrifice, but I think Black needs to advance some pawns for the purpose of creating contact with the enemy. This would cause White to pause in his queen-side advances. } 32...g5 33. Bc3 Be5 34. Nxe4 Nxe4 35. Bxe5 Rxe5 36. f3 Bg6 37. fxe4 Ke7 $16 ) 33. Bc3 e3 ( { Now it's too late for } 33...g5 $4 34. Bxf6 Kxf6 35. Nxe4+ ) 34. Bd4 ( 34. fxe3 fxe3 35. Bd4 Bf4 ) 34...Bxc5 ( 34...exf2+ { Black might have seen this as a bad move because of the implied simplification, but it does get rid of a White pawn near Kg1 and it doesn't just lose a pawn. } 35. Bxf2 $16 ) 35. Bxc5 Re5 ( 35...exf2+ 36. Bxf2 Ne4 37. b5 ) 36. fxe3 f3 37. gxf3 ( 37. g4 $2 { leaves Pf3 on the board, in White's camp and that's dangerous, compared to simply capturing it } ) 37...Bxf3 { White is better on the queen-side and now has a share of the center under control (Bc5 & Pe3 work together well) , but Kg1 is a little exposed, so he should improve that before proceeding with his strengths. } 38. Kh2 ( 38. Rb2 ) 38...Be4 39. Rb2 Rh5 40. Rf1 { activating the piece, preventing ...Nf6-g4+ and in place to defend Ph3 } 40...a6 ( 40...g5 41. Rbf2 Rh6 42. Bd4 g4 43. Rxf6+ $18 ) 41. Bd4 Bf5 { Black does all he can to avoid too many exchanges; he's also threatening Ph3. } 42. Rf3 Ne4 ( 42...Be4 43. Rf4 Bf5 44. h4 ) 43. b5 axb5 44. cxb5 cxb5 45. Rxb5 { How convenient for White, to end these exchanges by pinning Bf5! } 45...g6 46. a4 Nd2 ( 46...Ng5 47. Rfxf5+ gxf5 48. Rxf5+ Kg6 ( 48...Ke8 49. Kg2 h6 50. a5 Kd7 ( 50...Rxh3 $4 51. Rxg5 ) 51. a6 Kc7 52. a7 Kb7 53. Rf8 ) 49. Rf6+ Kg7 50. Rf4+ Kg6 51. h4 ) 47. Rf4 Rxh3+ 48. Kg2 Rh5 49. a5 Ke6 { unpinning Bf5 and threatening ...Bh3+ or ...Be4+ to win Rb5 } 50. Re5+ Kd6 51. a6
1-0
</textarea><br /><input type="button" value="Load PGN" onclick="mybrd.chessgame.loadPGN(pgnsample.value)" />
</div>
</td>
</tr>
</table>
</body>
</html>
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