chessClient.js

const pieceToText = {
    "K": "♔",
    "Q": "♕",
    "R": "♖",
    "B": "♗",
    "N": "♘",
    "P": "♙",
    "k": "♚",
    "q": "♛",
    "r": "♜",
    "b": "♝",
    "n": "♞",
    "p": "♟",
};
const initialFen = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 0";
var board;
let nextMoves = [];
let selectedPiece;

function boardToHTML(blackPerspective=false){
    $("#board").html("");
    let table = document.createElement("table");
    let currentRow;
    let trueIndex = blackPerspective ? 63 : 0;
    let trueIndexModifier = blackPerspective ? -1 : 1;
    for(i=0; i<64; i++){
        if(i % 8 == 0){
            if(currentRow)
            table.appendChild(currentRow);
            currentRow = document.createElement("tr");
        }
        
        let currentColumn = document.createElement("td");
        if((Math.floor(i/8) + (i % 8)) % 2 == 0)
            currentColumn.classList.add("light-cell");
        else
            currentColumn.classList.add("dark-cell");
        
        if(board.array[trueIndex])
            currentColumn.innerHTML = pieceToText[board.array[trueIndex].type];
        currentColumn.setAttribute("id", trueIndex);
        currentRow.appendChild(currentColumn);
        
        trueIndex += trueIndexModifier;
    }
    table.appendChild(currentRow);
    $("#board").append(table);

    nextMoves = board.getNextMoves();
}

function highlightMoves(index){
    let moves = nextMoves[index];
    if(moves)
        for(move of moves) // jshint ignore:line
            $("#"+String(move)).addClass("highlight");
}

function unselect(){
    $("#" + selectedPiece).removeClass("selected");
    selectedPiece = null;
    $(".highlight").removeClass("highlight");
}

function getThisPlayer(){
    return sessionStorage.getItem("player");
}

function select(index){
    unselect();
    $("#" + index).addClass("selected");
    selectedPiece = index;
    highlightMoves(index);
}

function processClick(socket, index, Players){
    // jshint ignore:start
    if(selectedPiece === index)
        unselect();
    else if(selectedPiece == null && board.array[index] && board.player == getThisPlayer() && board.player == board.array[index].player)
        select(index);
    else if(selectedPiece == null && board.array[index]?.player == changePlayer(getThisPlayer()))
        unselect();
    else if(board.array[index]?.player == getThisPlayer() && board.player == getThisPlayer()) 
        select(index);
    else if(selectedPiece != null){
        if(nextMoves[selectedPiece].includes(Number.parseInt(index))){
            // Make Move in client early
            board.makeMove(selectedPiece, index);
            postMove(Players, true);
            socket.emit("makeMove", sessionStorage.getItem("gameId"), selectedPiece, index);
        }
        else
        unselect();
        selectedPiece = null;
    }
    // jshint ignore:end
}

function postMove(Players, early=false){
    boardToHTML(getThisPlayer() == Players.black);
    if(!early){
    nextMoves = board.getNextMoves();
    if(board.isCheck(sessionStorage.getItem("player")))
        alert("You're in check");
    }
}