replace all 'var' declarations with 'let'

js/chess.js

@@ -1,13 +1,13 @@
 'use strict';
 
-var gun = Gun({
+let gun = Gun({
    peers: ['https://jessemcdonald.info/gun'],
    /* workaround for persistent errors accumulating which break synchronization */
    localStorage: false,
 });
 
 let initialBoard = (function (){
-   var init = JSON.stringify({
+   let init = JSON.stringify({
       light: [
          'rnbqkbnr',
          'pppppppp',
@@ -63,24 +63,24 @@ function boardGet(board, where, side){
          return board.phantom.type[0];
       }
    } else {
-      var column = 'abcdefgh'.indexOf(where[0]);
+      let column = 'abcdefgh'.indexOf(where[0]);
-      var row = Number(where[1]) - 1;
+      let row = Number(where[1]) - 1;
       return board[side][row][column];
    }
 }
 
 function boardPut(board, where, side, piece){
    side = normalizeSide(side);
-   var column = 'abcdefgh'.indexOf(where[0]);
+   let column = 'abcdefgh'.indexOf(where[0]);
-   var row = Number(where[1]) - 1;
+   let row = Number(where[1]) - 1;
-   var data = board[side][row];
+   let data = board[side][row];
-   var prefix = data.substring(0, column);
+   let prefix = data.substring(0, column);
-   var suffix = data.substring(column + 1, 8);
+   let suffix = data.substring(column + 1, 8);
    board[side][row] = prefix + piece + suffix;
 }
 
 function countMoves(board) {
-   var n = 0;
+   let n = 0;
    while (board && board.prior) {
       if (board.prior.player !== board.player) {
          ++n;
@@ -91,8 +91,8 @@ function countMoves(board) {
 }
 
 function offsetSquare(from, columnsRight, rowsUp){
-   var column = 'abcdefgh'.indexOf(from[0]);
+   let column = 'abcdefgh'.indexOf(from[0]);
-   var row = Number(from[1]) - 1;
+   let row = Number(from[1]) - 1;
 
    if (column < 0 || column > 7 || row < 0 || row > 7) {
       return null;
@@ -109,14 +109,14 @@ function offsetSquare(from, columnsRight, rowsUp){
 }
 
 function validDestination(board, side, where, canCapture){
-   var ours = boardGet(board, where, side);
+   let ours = boardGet(board, where, side);
-   var theirs = boardGet(board, where, otherSide(side));
+   let theirs = boardGet(board, where, otherSide(side));
    return ((theirs === ' ') ? (ours === ' ') : canCapture);
 }
 
 function scanPath(accum, board, side, from, canCapture, columnsLeft, rowsUp, remainder){
    while (true) {
-      var there = offsetSquare(from, columnsLeft, rowsUp);
+      let there = offsetSquare(from, columnsLeft, rowsUp);
       if (!there || !validDestination(board, side, there, canCapture)) { return; }
       accum.push(there);
       if (boardGet(board, there, otherSide(side)) !== ' ' || remainder < 1) { return; }
@@ -150,7 +150,7 @@ function legalMoves(board, side, type, from, canCapture){
 
    const ortho = [[-1, 0], [1, 0], [0, -1], [0, 1]];
    const diag = [[-1, -1], [-1, 1], [1, -1], [1, 1]];
-   var legals = [];
+   let legals = [];
 
    if (from === 'phantom') {
       from = board.phantom.from;
@@ -223,7 +223,7 @@ function legalMoves(board, side, type, from, canCapture){
                if (boardGet(board, there, otherSide(side)) !== ' ') {
                   legals.push(there);
                } else {
-                  var otherBoard = board;
+                  let otherBoard = board;
                   while (otherBoard && otherBoard.move && otherBoard.move.side[0] === side[0]) {
                      otherBoard = otherBoard.prior;
                   }
@@ -250,26 +250,26 @@ function legalMoves(board, side, type, from, canCapture){
 }
 
 function movePiece(priorBoard, side, from, to){
-   var other = otherSide(side);
+   let other = otherSide(side);
-   var type = boardGet(priorBoard, from, side);
+   let type = boardGet(priorBoard, from, side);
-   var took = boardGet(priorBoard, to, other);
+   let took = boardGet(priorBoard, to, other);
-   var replacedFrom = to;
+   let replacedFrom = to;
-   var replaced = boardGet(priorBoard, replacedFrom, side);
+   let replaced = boardGet(priorBoard, replacedFrom, side);
-   var alongside = boardGet(priorBoard, from, other);
+   let alongside = boardGet(priorBoard, from, other);
-   var actuallyFrom = (from === 'phantom') ? priorBoard.phantom.from : from;
+   let actuallyFrom = (from === 'phantom') ? priorBoard.phantom.from : from;
 
    const legals = legalMoves(priorBoard, side, type, from, alongside === ' ');
    if (!legals.includes(to)) {
       return priorBoard;
    }
 
-   var undoBoard = priorBoard;
+   let undoBoard = priorBoard;
    if (undoBoard.subsequent) {
       undoBoard = cloneJSON(undoBoard);
       delete undoBoard.subsequent;
    }
 
-   var board = cloneJSON(undoBoard);
+   let board = cloneJSON(undoBoard);
    board.prior = undoBoard;
 
    board.timestamp = new Date().getTime();
@@ -308,7 +308,7 @@ function movePiece(priorBoard, side, from, to){
       alongside = 'q';
    }
    if (type === 'p' && alongside === ' ' && replaced === ' ' && to[0] !== actuallyFrom[0]) {
-      var otherBoard = priorBoard;
+      let otherBoard = priorBoard;
       while (otherBoard && otherBoard.move && otherBoard.move.side[0] === side[0]) {
          otherBoard = otherBoard.prior;
       }
@@ -351,7 +351,7 @@ function movePiece(priorBoard, side, from, to){
 }
 
 function renderHistory(board) {
-   var list = [];
+   let list = [];
 
    while (board && board.move) {
       list.push(board.move);
@@ -362,8 +362,8 @@ function renderHistory(board) {
    const SHY = '\u00ad'  /* soft hyphen */
    const ZWSP = '\u200b';  /* zero-width space */
 
-   var result = '';
+   let result = '';
-   var n = 0;
+   let n = 0;
 
    while (list.length > 0) {
       const move = list.pop();
@@ -434,8 +434,8 @@ function pieceStopDrag(ev, ui){
 }
 
 function placePiece(where, type, count){
-   var piece_id = 'cb_piece_' + type + '_' + count;
+   let piece_id = 'cb_piece_' + type + '_' + count;
-   var piece = $($('#' + piece_id)[0] || $('#cb_piece_' + type + ' img').clone());
+   let piece = $($('#' + piece_id)[0] || $('#cb_piece_' + type + ' img').clone());
    piece.attr('style', '');
    piece.attr('id', piece_id);
    piece.data({ type: type, location: where });
@@ -459,26 +459,26 @@ function renderBoard(board){
    $('#cb_phantom').appendTo('#cb_hidden');
 
    for (const side of ['light', 'dark']) {
-      var counters = {};
+      let counters = {};
-      for (var row = 0; row < 8; ++row) {
+      for (let row = 0; row < 8; ++row) {
-         for (var column = 0; column < 8; ++column) {
+         for (let column = 0; column < 8; ++column) {
-            var here = 'abcdefgh'[column] + String(row+1);
+            let here = 'abcdefgh'[column] + String(row+1);
-            var type = board[side][row][column];
+            let type = board[side][row][column];
             if (type !== ' ') {
                if (!counters[type]) {
                   counters[type] = 0;
                }
-               var count = ++counters[type];
+               let count = ++counters[type];
                placePiece(here, type + side[0], count);
             }
          }
       }
    }
 
-   var clss = isLight(board.player) ? '.cb-lt-piece' : '.cb-dk-piece';
+   let clss = isLight(board.player) ? '.cb-lt-piece' : '.cb-dk-piece';
 
    if (board.phantom) {
-      var where = board.phantom.from;
+      let where = board.phantom.from;
       placePiece('phantom', board.phantom.type, 'ph');
       $('#cb_phantom').appendTo('#cb_' + where);
       $('#cb_board .ui-draggable').draggable('disable');
@@ -499,7 +499,7 @@ function renderBoard(board){
       $('#cb_' + board.move.to).addClass('cb-end');
    }
 
-   var msg = '';
+   let msg = '';
    if (board.move && board.move.took === 'k') {
       msg = (isDark(board.move.side) ? 'Dark' : 'Light') + ' player won!';
    } else {
@@ -568,32 +568,32 @@ function setCurrentBoard(board){
 }
 
 function randomId(){
-   var res = '';
+   let res = '';
-   for (var i = 0; i < 4; ++i) {
+   for (let i = 0; i < 4; ++i) {
-      var part = Math.floor(Math.random() * 65536).toString(16);
+      let part = Math.floor(Math.random() * 65536).toString(16);
       res = res + ('0000'.substring(part.length, 4) + part);
    }
    return res;
 }
 
-var PacoSakoUUID = '7c38edd4-c931-49c8-9f1a-84de560815db';
+let PacoSakoUUID = '7c38edd4-c931-49c8-9f1a-84de560815db';
 
 function putState(board){
-   var boardElem = $('#cb_board');
+   let boardElem = $('#cb_board');
-   var gameId = boardElem.data('gameId');
+   let gameId = boardElem.data('gameId');
-   var game = gun.get(PacoSakoUUID).get('games').get(gameId);
+   let game = gun.get(PacoSakoUUID).get('games').get(gameId);
    boardElem.data('last_state', cloneJSON(board));
    game.put({ board: JSON.stringify(board) });
    putMeta();
 }
 
 function putMeta(){
-   var board = $('#cb_board').data('board');
+   let board = $('#cb_board').data('board');
-   var gameId = $('#cb_board').data('gameId');
+   let gameId = $('#cb_board').data('gameId');
-   var lightName = $('#cb_light_name').val();
+   let lightName = $('#cb_light_name').val();
-   var darkName = $('#cb_dark_name').val();
+   let darkName = $('#cb_dark_name').val();
-   var meta = gun.get(PacoSakoUUID).get('meta').get(gameId);
+   let meta = gun.get(PacoSakoUUID).get('meta').get(gameId);
-   var stat = (board.move && board.move.took === 'k') ? 'mate' : null;
+   let stat = (board.move && board.move.took === 'k') ? 'mate' : null;
    meta.put({
       gameId: gameId,
       lightName: lightName,
@@ -605,8 +605,8 @@ function putMeta(){
 }
 
 function switchGameId(newId){
-   var boardElem = $('#cb_board');
+   let boardElem = $('#cb_board');
-   var gameId = boardElem.data('gameId');
+   let gameId = boardElem.data('gameId');
 
    if (newId === gameId) {
       return;
@@ -631,7 +631,7 @@ function switchGameId(newId){
    closeNotifications();
 
    /* this will be the starting state if no data is received from peers */
-   var newBoard = initialBoard();
+   let newBoard = initialBoard();
    setCurrentBoard(newBoard);
    boardElem.data('last_state', cloneJSON(newBoard));
 
@@ -656,7 +656,7 @@ function switchGameId(newId){
       }
    });
 
-   var selOpt = $('#cb_game_' + newId);
+   let selOpt = $('#cb_game_' + newId);
    if (selOpt.length === 1) {
       $('#cb_select_game')[0].selectedIndex = selOpt.index();
    } else {
@@ -755,13 +755,13 @@ $(function (){
          $(this).droppable('disable');
       },
       drop: function(ev, ui) {
-         var dragged = ui.draggable;
+         let dragged = ui.draggable;
-         var type = dragged.data('type');
+         let type = dragged.data('type');
-         var from = dragged.data('location');
+         let from = dragged.data('location');
-         var to = this.id.replace(/^cb_/, '');
+         let to = this.id.replace(/^cb_/, '');
          dragged.appendTo('#cb_hidden');
 
-         var newBoard = movePiece($('#cb_board').data('board'), type[1], from, to);
+         let newBoard = movePiece($('#cb_board').data('board'), type[1], from, to);
          renderBoard(newBoard);
          putState(newBoard);
       },
@@ -806,7 +806,7 @@ $(function (){
    });
 
    $('#cb_nav_first').on('click', function(){
-      var board = $('#cb_board').data('visible_board');
+      let board = $('#cb_board').data('visible_board');
       if (board) {
          while (board.prior) {
             board = stepBack(board);
@@ -816,7 +816,7 @@ $(function (){
    });
 
    $('#cb_nav_prev_turn').on('click', function(){
-      var board = $('#cb_board').data('visible_board');
+      let board = $('#cb_board').data('visible_board');
       board = stepBack(board);
       const player = board.player;
       while (board.prior && board.prior.player === player) {
@@ -834,7 +834,7 @@ $(function (){
    });
 
    $('#cb_nav_next_turn').on('click', function(){
-      var board = $('#cb_board').data('visible_board');
+      let board = $('#cb_board').data('visible_board');
       const player = board.player;
       board = stepForward(board);
       while (board.subsequent && board.player === player) {
@@ -854,9 +854,9 @@ $(function (){
    });
 
    $('#cb_pass').on('click', function(){
-      var board = $('#cb_board').data('board');
+      let board = $('#cb_board').data('board');
       if (!board.phantom) {
-         var newBoard = cloneJSON(board);
+         let newBoard = cloneJSON(board);
          newBoard.prior = board;
          newBoard.move = { side: board.player, pass: true };
          newBoard.player = otherSide(board.player);
@@ -866,11 +866,11 @@ $(function (){
    });
 
    $('#cb_select_game').on('change', function(){
-      var optIndex = $('#cb_select_game')[0].selectedIndex;
+      let optIndex = $('#cb_select_game')[0].selectedIndex;
       if (optIndex === 0) {
          switchGameId(randomId());
       } else if (optIndex >= 1) {
-         var opt = $('#cb_select_game option')[optIndex];
+         let opt = $('#cb_select_game option')[optIndex];
          if (opt) {
             switchGameId(opt.id.replace(/^cb_game_/, ''));
          }
@@ -890,7 +890,7 @@ $(function (){
    $('#cb_light_name').on('input', updateMeta);
    $('#cb_dark_name').on('input', updateMeta);
 
-   var gameId = location.hash.replace(/^#\//, '');
+   let gameId = location.hash.replace(/^#\//, '');
    if (gameId.length !== 16) {
       gameId = randomId();
    }
@@ -902,7 +902,7 @@ $(function (){
 
       const then = opt.data('then');
       const now = new Date().getTime();
-      var age_str = '';
+      let age_str = '';
       if (then > now) {
          age_str = ' (future)';
       } else if ((now - then) < 60*60*1000) {
@@ -925,7 +925,7 @@ $(function (){
          const moves = !d.moves ? '' :
             (', ' + d.moves + (d.moves === 1 ? ' move' : ' moves'));
 
-         var opt = $('#cb_game_' + d.gameId);
+         let opt = $('#cb_game_' + d.gameId);
 
          if (!(d.lightName || d.darkName) && !d.moves && d.gameId !== $('#cb_board').data('gameId')) {
             if (opt.length >= 1) {
@@ -937,7 +937,7 @@ $(function (){
                opt.attr('id', 'cb_game_' + d.gameId);
             }
 
-            var stat = '';
+            let stat = '';
             if (d.status) {
                stat = ', ' + d.status;
             }
@@ -949,8 +949,8 @@ $(function (){
             opt.appendTo('#cb_select_game');
             updateTitle(opt);
 
-            var select = $('#cb_select_game');
+            let select = $('#cb_select_game');
-            var list = select.children('.cb-game-option').get();
+            let list = select.children('.cb-game-option').get();
             list.sort(function(a,b) {
                const then_a = $(a).data('then');
                const then_b = $(b).data('then');
@@ -962,7 +962,7 @@ $(function (){
             }
          }
 
-         var selOpt = $('#cb_game_' + $('#cb_board').data('gameId'));
+         let selOpt = $('#cb_game_' + $('#cb_board').data('gameId'));
          if (selOpt.length === 1) {
             $('#cb_select_game')[0].selectedIndex = selOpt.index();
          } else {
@@ -979,8 +979,8 @@ $(function (){
 
    window.setInterval(function(){
       const peers = gun._.opt.peers;
-      var n_open = 0;
+      let n_open = 0;
-      var n_total = 0;
+      let n_total = 0;
       for (const peerId in peers) {
          ++n_total;
          try {
@@ -1003,7 +1003,7 @@ $(function (){
    }, 1000);
 
    window.onpopstate = function(event){
-      var gameId = location.hash.replace(/^#\//, '');
+      let gameId = location.hash.replace(/^#\//, '');
       if (gameId.length === 16) {
          switchGameId(gameId);
       }