Chess.com Piece Numbers

Adds piece number data to pieces in the chess board

You will need to install an extension such as Tampermonkey, Greasemonkey or Violentmonkey to install this script.

You will need to install an extension such as Tampermonkey or Violentmonkey to install this script.

You will need to install an extension such as Tampermonkey or Violentmonkey to install this script.

You will need to install an extension such as Tampermonkey or Userscripts to install this script.

You will need to install an extension such as Tampermonkey to install this script.

You will need to install a user script manager extension to install this script.

(I already have a user script manager, let me install it!)

You will need to install an extension such as Stylus to install this style.

You will need to install an extension such as Stylus to install this style.

You will need to install an extension such as Stylus to install this style.

You will need to install a user style manager extension to install this style.

You will need to install a user style manager extension to install this style.

You will need to install a user style manager extension to install this style.

(I already have a user style manager, let me install it!)

// ==UserScript==
// @name         Chess.com Piece Numbers
// @namespace    https://theusaf.org
// @version      0.1.1
// @description  Adds piece number data to pieces in the chess board
// @author       theusaf
// @match        https://www.chess.com/**
// @icon         https://www.google.com/s2/favicons?domain=chess.com
// @grant        none
// @license      MIT
// ==/UserScript==

let tries = 0;

function init() {
  const board = document.querySelector("chess-board,wc-chess-board"),
  pieces = {
    black: {
      p: 2 // to fix promotion stuff
    },
    white: {
      p: 2
    }
  };

  if (board) {
    const observer = new MutationObserver((mutations, observer) => {
         console.log(mutations);
      const attributeMutations = new Set();
      for (const mutation of mutations) {
        if (mutation.type === "childList") {
          const {addedNodes, removedNodes} = mutation;
          for (const node of addedNodes) {
            if (node.nodeName !== "DIV") {continue;}
            if (Array.from(node.classList)?.includes("piece")) {
              addPiece(node);
            }
          }
          for (const node of removedNodes) {
            if (node.nodeName !== "DIV") {continue;}
            if (Array.from(node.classList)?.includes("piece")) {
              removePiece(node);
            }
          }
        } else {
          const filter = (mutation) => {
            return (/piece/.test(mutation.oldValue) ||
            /piece/.test(mutation.target.className)) &&
            (!/dragging/.test(mutation.target.className) &&
            !/dragging/.test(mutation.oldValue) &&
            mutation.oldValue !== null);
          };
          if (filter(mutation)) {
            attributeMutations.add(mutation);
          }
        }
      }
      const out = [],
        moveSquaresProcessed = new Set(),
        toSwap = new Set();
      for (const mutation of attributeMutations) {
        out.push(mutation);
        const piecePosition = getPieceSquare(mutation.target.className),
          [pieceTeam, pieceType] = getPieceType(mutation.target.className),
          [originalPieceTeam, originalPieceType] = getPieceType(mutation.oldValue);
        if (piecePosition in moveSquaresProcessed) {continue;}
        moveSquaresProcessed.add(piecePosition);
        let shouldContinue = false;
        // console.log(piecePosition, pieceTeam, pieceType, originalPieceTeam, originalPieceType)
        for (const swap of toSwap) {
          const {team, type, swapWith} = swap;
          if (pieceTeam === team && pieceType === type) {
            console.log("swapping");
            swapPieces(mutation.target, swapWith);
            toSwap.delete(swap);
            shouldContinue = true;
            break;
          }
        }
        if (shouldContinue) {continue;}
        if (pieceTeam === originalPieceTeam && pieceType === originalPieceType) {
          // no change required
        } else {
          // uh oh, need to swap!
          toSwap.add({
            team: originalPieceTeam,
            type: originalPieceType,
            swapWith: mutation.target
          });
        }
      }
      if (out.length) {
        /*console.log(out.map(mutation => {
          return [`${mutation.oldValue} --> ${mutation.target.className}`, mutation.target];
        }));*/
        // Check for any abnormalities and fix issues
        moveSquaresProcessed.clear();
        for (const mutation of attributeMutations) {
          const piecePosition = getPieceSquare(mutation.target.className),
            currentPiece = getPieceType(mutation.target.className).join(""),
            originalPiece = mutation.target.getAttribute("original-piece");
          if (piecePosition in moveSquaresProcessed) {continue;}
          moveSquaresProcessed.add(piecePosition);
          if (!currentPiece || !piecePosition) {continue;}
          if (currentPiece !== originalPiece) {
            const pieces = [...document.querySelectorAll(`[original-piece=${currentPiece}]`)];
            for (const piece of pieces) {
              const pieceOrignalPiece = piece.getAttribute("original-piece"),
                pieceCurrentPiece = getPieceType(piece.className).join("");
              if (pieceOrignalPiece !== pieceCurrentPiece) {
                console.log("Swapping #2", mutation.target, piece);
                swapPieces(piece, mutation.target);
                // swap original pieces also
                mutation.target.setAttribute("original-piece", pieceOrignalPiece);
                piece.setAttribute("original-piece", originalPiece);
                break;
              }
            }
          }
        }
      }
    });
    observer.observe(board, {
      childList: true,
      subtree: true,
      attributeFilter: ["class"],
      attributeOldValue: true
    });
    const existingPieces = board.querySelectorAll(".piece");
    for (const piece of existingPieces) {
      addPiece(piece);
    }

    // check if it is just a temporary board
    setTimeout(() => {
      if (!board.isConnected) {
        if (++tries > 10) {return;}
        setTimeout(init, 500);
      }
    }, 500)
  } else {
    if (++tries > 10) {return;}
    setTimeout(init, 500);
  }

  function swapPieces(a, b) {
    const myNumber = a.getAttribute("piece-number"),
      myOriginalPiece = a.getAttribute("original-piece");
    a.setAttribute("piece-number", b.getAttribute("piece-number"));
    a.setAttribute("original-piece", b.getAttribute("original-piece"));
    b.setAttribute("piece-number", myNumber);
    b.setAttribute("original-piece", myOriginalPiece);
    if (a.getAttribute("piece-number") === "null") addPiece(a);
    if (b.getAttribute("piece-number") === "null") addPiece(b);
  }
  function getPieceSquare(name) {
    const piece = name.split(" ").find(word => /^square/.test(word));
    return piece?.split("-")[1];
  }
  function getPieceType(name) {
    const piece = name.split(" ").find(word => word.length === 2 && /^[wb]/.test(word));
    return piece?.split("") || [];
  }
  function addPiece(piece) {
    console.log("new piece", piece)
    const colorPieces = piece.classList[1][0] === "w" ? pieces.white : pieces.black,
    actualPiece = piece.classList[1][1];
    if (typeof colorPieces[actualPiece] !== "number") {colorPieces[actualPiece] = 0;}
    colorPieces[actualPiece]++;
    piece.setAttribute("piece-number", colorPieces[actualPiece]);
    piece.setAttribute("original-piece", getPieceType(piece.className).join(""));
  }
  function removePiece(piece) {
    const colorPieces = piece.classList[1][0] === "w" ? pieces.white : pieces.black,
    actualPiece = piece.classList[1][1];
    if (typeof colorPieces[actualPiece] !== "number") {colorPieces[actualPiece] = 0;}
    colorPieces[actualPiece]--;
  }
}

init();