Return undefined when get/remove called on empty square

README.md

@@ -284,15 +284,15 @@ chess.fen()
 
 ### .get(square)
 
-Returns the piece on the square:
+Returns the piece on the square. Returns `undefined` if the square is empty.
 
 ```ts
 chess.put({ type: PAWN, color: BLACK }, 'a5') // put a black pawn on a5
 
 chess.get('a5')
 // -> { type: 'p', color: 'b' },
 chess.get('a6')
-// -> null
+// -> undefined
 ```
 
 ### .getCastlingRights(color)
@@ -844,7 +844,8 @@ chess.put({ type: 'k', color: 'w' }, 'h1') // fail - two kings
 
 ### .remove(square)
 
-Remove and return the piece on _square_.
+Remove and return the piece on _square_. Returns `undefined` if the square is
+already empty.
 
 ```ts
 chess.clear()
@@ -856,7 +857,7 @@ chess.remove('a5')
 chess.remove('h1')
 // -> { type: 'k', color: 'w' },
 chess.remove('e1')
-// -> null
+// -> undefined
 ```
 
 ### .reset()

__tests__/get.test.ts

@@ -13,12 +13,12 @@ test('get', () => {
 //   expect(chess.get('A7' as Square)).toEqual({ type: PAWN, color: BLACK })
 // })
 
-test('get - returns false for empty square', () => {
+test('get - returns undefined for empty square', () => {
   const chess = new Chess()
-  expect(chess.get('a4')).toEqual(false)
+  expect(chess.get('a4')).toEqual(undefined)
 })
 
-test('get - returns false for invalid square', () => {
+test('get - returns undefined for invalid square', () => {
   const chess = new Chess()
-  expect(chess.get('bad-square' as Square)).toEqual(false)
+  expect(chess.get('bad-square' as Square)).toEqual(undefined)
 })

__tests__/remove.test.ts

@@ -11,17 +11,17 @@ import {
 test('remove - returns piece', () => {
   const chess = new Chess()
   expect(chess.remove('d1')).toEqual({ type: QUEEN, color: WHITE })
-  expect(chess.get('d1')).toEqual(false)
+  expect(chess.get('d1')).toEqual(undefined)
 })
 
-test('remove - returns false for empty square', () => {
+test('remove - returns undefined for empty square', () => {
   const chess = new Chess()
-  expect(chess.remove('e4')).toEqual(false)
+  expect(chess.remove('e4')).toEqual(undefined)
 })
 
-test('remove - returns false for invalid square', () => {
+test('remove - returns undefined for invalid square', () => {
   const chess = new Chess()
-  expect(chess.remove('bad_square' as Square)).toEqual(false)
+  expect(chess.remove('bad_square' as Square)).toEqual(undefined)
 })
 
 test('remove - removing white kingside rook loses castling right', () => {

src/chess.ts

@@ -768,8 +768,8 @@ export class Chess {
     this.load(DEFAULT_POSITION)
   }
 
-  get(square: Square) {
-    return this._board[Ox88[square]] || false
+  get(square: Square): Piece | undefined {
+    return this._board[Ox88[square]]
   }
 
   put({ type, color }: { type: PieceSymbol; color: Color }, square: Square) {
@@ -822,7 +822,7 @@ export class Chess {
     return true
   }
 
-  remove(square: Square) {
+  remove(square: Square): Piece | undefined {
     const piece = this.get(square)
     delete this._board[Ox88[square]]
     if (piece && piece.type === KING) {