taking turns

src/App.js

@@ -14,13 +14,18 @@ function Square({value, onSquareClick}) {
 }
 
 function App() {
-
+  const [xIsNext, setXIsNext] = useState(true);
   const [squares, setSquares] = useState(Array(9).fill(null));
   
   function handleClick(i) {
     const nextSquares = squares.slice();
+    if (xIsNext) {
       nextSquares[i] = "X";
+    } else { 
+      nextSquares[i] = "O";
+    }
     setSquares(nextSquares);
+    setXIsNext(!xIsNext);
   }
 
   return (