lib: ship wikimedia piece svgs as built-in data urls

lib/chessboard.js

@@ -1,5 +1,7 @@
 /* eslint-env browser */
 
+import * as pieces from './pieces.svg.js';
+
 // ---------------------------------------------------------------------------
 // Constants
 // ---------------------------------------------------------------------------
@@ -439,10 +441,10 @@ function expandConfig(config) {
   // draggable must be true if sparePieces is enabled
   if (config.sparePieces) config.draggable = true;
 
-  // default piece theme is wikipedia
+  // default piece theme is built-in svg
   if (!Object.prototype.hasOwnProperty.call(config, 'pieceTheme') ||
     (typeof config.pieceTheme !== 'string' && typeof config.pieceTheme !== 'function')) {
-    config.pieceTheme = 'img/chesspieces/wikipedia/{piece}.png';
+    config.pieceTheme = '{piece}';
   }
 
   // animation speeds
@@ -898,11 +900,12 @@ class Chessboard {
 
   #buildPiece(piece, hidden, id) {
     const pieceEl = new Image(this.#squareSize, this.#squareSize);
+    const src = this.#buildPieceImgSrc(piece);
 
+    pieceEl.src = src === piece ? pieces[src] : src;
     pieceEl.alt = '';
     pieceEl.classList.add(ClassNameLookup.piece);
     pieceEl.dataset.piece = piece;
-    pieceEl.src = this.#buildPieceImgSrc(piece);
 
     if (typeof id === 'string' && id.length > 0) {
       pieceEl.id = id;