+ getPotentialMovesFrom([x, y]) {
+ let moves = super.getPotentialMovesFrom([x,y]);
+ // Add en-passant captures from this square:
+ const L = this.epSquares.length;
+ if (!this.epSquares[L - 1]) return moves;
+ const squares = this.epSquares[L - 1];
+ const S = squares.length;
+ // Object describing the removed opponent's piece:
+ const pipoV = new PiPo({
+ x: squares[S-1].x,
+ y: squares[S-1].y,
+ c: V.GetOppCol(this.turn),
+ p: this.getPiece(squares[S-1].x, squares[S-1].y)
+ });
+ // Check if existing non-capturing moves could also capture en passant
+ moves.forEach(m => {
+ if (
+ m.appear[0].p != V.PAWN && //special pawn case is handled elsewhere
+ m.vanish.length <= 1 &&
+ [...Array(S-1).keys()].some(i => {
+ return m.end.x == squares[i].x && m.end.y == squares[i].y;
+ })
+ ) {
+ m.vanish.push(pipoV);
+ }
+ });
+ // Special case of the king knight's movement:
+ if (this.getPiece(x, y) == V.KING) {
+ V.steps[V.KNIGHT].forEach(step => {
+ const endX = x + step[0];
+ const endY = y + step[1];
+ if (
+ V.OnBoard(endX, endY) &&
+ [...Array(S-1).keys()].some(i => {
+ return endX == squares[i].x && endY == squares[i].y;
+ })
+ ) {
+ let enpassantMove = this.getBasicMove([x, y], [endX, endY]);
+ enpassantMove.vanish.push(pipoV);
+ moves.push(enpassantMove);
+ }
+ });
+ }
+ return moves;
+ }
+