title: finding winner on Tic-Tac-Toe game JavaScript
body: <p>I'm new to JavaScript and I'm building a Tic Tac Toe game with JavaScript and ruby. 
  Presently I've got code as below but I could not make the function of telling the winner work. Wondering if anybody can help me here? Thank you in advance!</p>
  
  <pre><code>const initialBoard = document.getElementById('navbar-new');
  initialBoard.addEventListener("click", (e) =&gt; {
    e.preventDefault();
    alert('Game starts!');
    grid_0.innerText = '';
    grid_1.innerText = '';
    grid_2.innerText = '';
    grid_3.innerText = '';
    grid_4.innerText = '';
    grid_5.innerText = '';
    grid_6.innerText = '';
    grid_7.innerText = '';
    grid_8.innerText = '';
  });
  
  const grid_0 = document.getElementById('grid-0');
  const grid_1 = document.getElementById('grid-1');
  const grid_2 = document.getElementById('grid-2');
  const grid_3 = document.getElementById('grid-3');
  const grid_4 = document.getElementById('grid-4');
  const grid_5 = document.getElementById('grid-5');
  const grid_6 = document.getElementById('grid-6');
  const grid_7 = document.getElementById('grid-7');
  const grid_8 = document.getElementById('grid-8');
  
  let currentPlayer = "X";
  
  function ticTac(){
    if (this.innerText !== "X" || this.innerText !== "O") {
      this.innerText = currentPlayer;
      currentPlayer = currentPlayer == "X" ? "O" : "X";
    }
  };
  
  document.getElementById("grid-0").onclick = ticTac;
  document.getElementById("grid-1").onclick = ticTac;
  document.getElementById("grid-2").onclick = ticTac;
  document.getElementById("grid-3").onclick = ticTac;
  document.getElementById("grid-4").onclick = ticTac;
  document.getElementById("grid-5").onclick = ticTac;
  document.getElementById("grid-6").onclick = ticTac;
  document.getElementById("grid-7").onclick = ticTac;
  document.getElementById("grid-8").onclick = ticTac;
  </code></pre>