2d:null 2e:["$","title",null,{"children":"Portable Game Notation | Nikita Sharov | Observable"}] 33:T42f,getHalfMoveDescription = { const colors = new Map([ ["w", "white"], ["b", "black"] ]); const pieces = new Map([ ["k", "king"], ["q", "queen"], ["r", "rook"], ["b", "bishop"], ["n", "knight"], ["p", "pawn"] ]); const getHalfMoveDescription = (move) => { let text = `${colors.get(move.color)} ${pieces.get(move.piece)}`; if (move.flags.includes("b") || move.flags.includes("n")) { text += ` goes to ${move.to} (from ${move.from}).`; } if (move.flags.includes("c")) { text += ` takes ${pieces.get(move.captured)} at ${move.to} (from ${move.from}).`; } if (move.flags.includes("k")) { if (move.color === "w") { text = `${colors.get(move.color)} castles kingside (king goes from e1 to g1, rook goes from h1 to f1).`; } else { text = `${colors.get(move.color)} castles kingside (king goes from e8 to g8, rook goes from h8 to f8).`; } } return toSentenceCase(text); } return getHalfMoveDescription; }34:[{"id":"ad80b1982e552295bdfe9a9a960d89723822460c6a8c537f36f3cdc1759cc753248d33b152983975fa1721c3c62d893ff9e959288d5435270f31069eeaae9f0c","href":"https://static.observableusercontent.com/files/ad80b1982e552295bdfe9a9a960d89723822460c6a8c537f36f3cdc1759cc753248d33b152983975fa1721c3c62d893ff9e959288d5435270f31069eeaae9f0c","name":"ivanchuk-wolff-1993.pgn","type":"application/octet-stream","lastModified":1610989800513.188,"size":1038},{"id":"2a61959e18e587183cbb1184e70a5877468b8498d684d5c3d0964b518079c8ffa7a997948f7f0ce82f546f2cf633f0b0177216ff6fe1cc2da2e18aa266b5fe1a","href":"https://static.observableusercontent.com/files/2a61959e18e587183cbb1184e70a5877468b8498d684d5c3d0964b518079c8ffa7a997948f7f0ce82f546f2cf633f0b0177216ff6fe1cc2da2e18aa266b5fe1a","name":"chessground.css","type":"text/css","lastModified":1611144134836.709,"size":16476}] 31:{"id":"c4ebb8b279057166","slug":"portable-game-notation","title":"Portable Game Notation","thumbnail":"6f162d554a1dc0b32206df46aafed063f3eafbf48150424402521074faf09f45","access_level":"public","create_time":"$D2021-01-18T14:13:23.365Z","update_time":"$D2021-02-22T17:40:33.215Z","view_time":null,"first_public_time":"$D2021-01-20T11:38:30.541Z","has_unpublished_edits":null,"fork":{"id":"53b63fd4bc61ddab","slug":"hello-chessground","title":"Hello, Chessground","owner":{"id":"6c49d8d38db08400","login":"nikita-sharov","name":"Nikita Sharov"}},"stars":2,"starred":false,"owner":{"type":"team","id":"6c49d8d38db08400","login":"nikita-sharov","name":"Nikita Sharov","avatar_url":"https://avatars-next.observableusercontent.com/544afb614871e9f3bee546cbff7e689f2a454464b16ac434007893bde877f2df","tier":"starter_2024"},"version":1281,"publish_version":1281,"role":null,"authored":false,"authors":[{"type":"individual","id":"ee7c67b988c5530c","login":"nikita-sharov","name":"Nikita Sharov","avatar_url":"https://avatars-next.observableusercontent.com/544afb614871e9f3bee546cbff7e689f2a454464b16ac434007893bde877f2df","tier":null}],"members":[{"type":"individual","id":"ee7c67b988c5530c","login":"nikita-sharov","name":"Nikita Sharov","avatar_url":"https://avatars-next.observableusercontent.com/544afb614871e9f3bee546cbff7e689f2a454464b16ac434007893bde877f2df","tier":null,"role":"editor"}],"comments":[],"custom_thumbnail":true,"trashed":false,"lapsed":null,"subscribed":null,"forks":2,"collection":{"id":"8c9a769cb96eee74","slug":"chess","title":"Chess","owner":{"id":"6c49d8d38db08400","login":"nikita-sharov","name":"Nikita Sharov"}},"type":"notebook","body":{"title":"Portable Game Notation","cells":[{"id":0,"value":"md`# Portable Game Notation\nis a plain text format for recording chess games (moves and metadata), developed by Steven J. Edwards “for easy reading and writing by human users and for easy parsing and generation by computer programs” in 1993.`","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":404,"value":"illustrateHeader()","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":121,"value":"html`

`","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":267,"value":"viewof positionIndex = createStepper(visibility) // see: https://observablehq.com/@observablehq/awaiting-visibility","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":762,"value":"illustrateMoves()","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":367,"value":"md`---\n## Data`","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":259,"value":"// game metadata\nheader = game.header()","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":408,"value":"// games for archival storage are required to provide following tags (as tag-value pairs),\n// known as the \"Seven Tag Roster\"\nsevenTagRoster = new Set([\n // the name of the tournament or match event\n \"Event\", \n\n // the location of the event, in 'City, Region COUNTRY' format ('City COUNTRY' in our case), \n // where COUNTRY is the three-letter International Olympic Committee country code\n \"Site\", \n\n // the starting date of the game, in YYYY.MM.DD format, '??' used for unknown values ('?' in our case)\n \"Date\",\n\n // the playing round ordinal of the game within the event\n \"Round\",\n\n // the player of the white pieces, in 'LastName, FirstName' format (in reverse order without comma, in our case)\n \"White\",\n\n // the player of the black pieces\n \"Black\",\n\n // the result of the game, in 'WhiteScore-BlackScore' format, or '*' for other, e.g., the game is ongoing\n \"Result\"\n])","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":269,"value":"// half-moves (aka ply, in plural) are not unique\nhalfMoves = game.history({verbose: true}) // returns moves in Standard (Short) Algebraic Notation (SAN) only otherwise","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":254,"value":"// see: https://www.chessgames.com/perl/chessgame?gid=1060353\ngame = {\n const game = new Chess();\n game.load_pgn(pgn);\n return game;\n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":242,"value":"Chess = require(\"chess.js@0.11\")","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":1278,"value":"pgn = FileAttachment(\"ivanchuk-wolff-1993.pgn\").text(); ","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":433,"value":"md`---\n## Representation`","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":724,"value":"illustrateHeader = () => {\n let literal = \"\"\n \n const addTagValuePair = (tag, value) => {\n if (value === \"?\") {\n return;\n }\n \n if (literal.length > 0) {\n literal += \" \";\n }\n \n literal += `[${decode(tag)} \"${decode(value)}\"]`;\n }; \n \n const addMandatoryTagValues = () => { \n sevenTagRoster.forEach((tag) => addTagValuePair(tag, header[tag]));\n };\n\n const addOptionalTagValues = () => {\n Object.keys(header).forEach((tag) => {\n if (!sevenTagRoster.has(tag)) {\n addTagValuePair(tag, header[tag]);\n }\n }); \n };\n \n addMandatoryTagValues();\n literal += \"
\" \n addOptionalTagValues();\n \n return md`${literal}`;\n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":825,"value":"decode = (text) => { \n if (clarifications.has(text)) {\n return clarify(text);\n }\n\n let result = \"\";\n const words = text.split(\" \");\n words.forEach((word) => {\n if (result.length > 0) {\n result += \" \";\n }\n\n if (clarifications.has(word)) {\n result += clarify(word);\n } else {\n result += word;\n }\n });\n\n return result;\n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":704,"value":"clarifications = new Map([\n [\"Interzonal\", \"Tournament organized by FIDE as a stage in the triennial World Championship cycle.\"],\n [\"SUI\", \"International Olympic Committee country code for Switzerland.\"],\n [\"1/2-1/2\", \"Draw, awarding each player a half-point in the traditional chess tournament scoring system.\"],\n [\"ECO\", \"Encyclopedia of Chess Openings, a reference system published in five volumes.\"],\n [\"D20\", \"Queen's Gambit Accepted, an ECO Volume D opening.\"],\n [\"PlyCount\", \"Number of half-moves played: one move consists of a turn by each player.\"]\n])","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":817,"value":"clarify = (text) => `${text}`","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":295,"value":"// in Forsyth-Edwards Notation (FEN)\ncurrentPosition = {\n const fen = positions[positionIndex];\n board.set({fen});\n highlightHalfMove(positionIndex);\n return fen;\n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":281,"value":"positions = {\n const game = new Chess();\n const initialPosition = game.fen();\n const positions = [initialPosition];\n halfMoves.forEach((move) => {\n game.move(move);\n const position = game.fen();\n positions.push(position);\n });\n \n return positions;\n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":95,"value":"// see: https://github.com/ornicar/chessground/blob/master/src/config.ts\nboard = {\n const container = document.getElementById(\"board-container\"); \n return Chessground(container, {viewOnly: true}); \n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":12,"value":"Chessground = (await require('https://bundle.run/chessground@7.9.3')).Chessground","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":733,"value":"illustrateMoves = () => {\n let literal = \"\";\n \n const prependSpace = () => {\n if (literal.length > 0) {\n literal += \" \";\n } \n };\n \n const addHalfMove = (move, number) => literal += `${move.san}`;\n \n const addMove = ([whiteMove, blackMove], number) => {\n prependSpace();\n literal += `${number}.`;\n const whiteMoveNumber = (number * 2) - 1;\n addHalfMove(whiteMove, whiteMoveNumber);\n if (blackMove !== undefined) {\n prependSpace();\n const blackMoveNumber = whiteMoveNumber + 1;\n addHalfMove(blackMove, blackMoveNumber);\n } \n }; \n \n const moves = getMoves(halfMoves);\n moves.forEach((move, index) => addMove(move, index + 1));\n \n const isClosedGame = () => header.Result !== \"*\";\n \n if (isClosedGame()) {\n prependSpace();\n literal += ` ${header.Result}`; // repeating the result in the header\n }\n \n return md`${literal}`;\n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":1175,"value":"highlightHalfMove = (positionIndex) => {\n let element = document.querySelector(\".half-move.current\");\n if (element != null) {\n element.classList.remove(\"current\");\n const previousHalfMoveNumber = element.dataset.number; // might be the last move of the game when looping \n element.innerText = halfMoves[previousHalfMoveNumber - 1].san;\n };\n \n if (positionIndex > 0) {\n const currentHalfMoveNumber = positionIndex;\n element = document.querySelector(`.half-move[data-number=\"${currentHalfMoveNumber}\"]`);\n element.classList.add(\"current\");\n const currentHalfMove = halfMoves[currentHalfMoveNumber - 1];\n const description = getHalfMoveDescription(currentHalfMove); \n element.innerHTML = `${currentHalfMove.san}`;\n }\n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":1187,"value":"$33","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":1190,"value":"toSentenceCase = (text) => text[0].toUpperCase() + text.slice(1, text.length)","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":809,"value":"getMoves = (halfMoves) => \n halfMoves.reduce((result, value, index, array) => {\n if ((index % 2) === 0) {\n const move = array.slice(index, index + 2)\n result.push(move);\n }\n\n return result;\n }, []);","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":681,"value":"createStepper = (visibility) => {\n const positionIndices = Array.from({length: positions.length}, (_, i) => i);\n const options = {\n delay: 1000,\n loop: false,\n firstStepDelay: 100,\n format: (_, index, values) => {\n const halfMoveCount = (values.length - 1).toString(); \n const halfMoveNumber = index.toString().padStart(halfMoveCount.length, \"0\");\n return `Ply: ${halfMoveNumber}/${halfMoveCount}`;\n },\n visibility\n };\n \n return stepper(positionIndices, options);\n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":263,"value":"import {stepper} from \"@nikita-sharov/stepper\"","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":265,"value":"html``","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":65,"value":"html`