Build Multiplayer Realtime Tic Tac Toe Game with Socket.io and Vue

In this article, we will develop a tic-tac-toe game from scratch using Vue. We will integrate the real time feature with socket.io, so that two players can play the game from different browsers at the same time.

Video Tutorial

Project creation

First, create a blank Vue project and in the app.vue,remove the hello world component and add the html for the grid. I copied the CSS from this tutorial.

We will define 9 blocks with id block_0 to block_8 with class block for each block.

You can find the Github code till now in this branch.
GitHub - nilmadhab/tic-tac-toe-youtube at grid-setup

Draw X and O on click

Now, we will define two variables in the data section:

1. content

2. turn
   

   Content will be an array of length 9, one element for each block of html, initialized with the empty string. When we click one block, we will change the value at that index of the content. Let’s define the function @click, and use it.
   We will draw the X and O based on the content array and on the click will trigger the draw function in each block.

Now, let’s define the draw function in the methodsection. If the value of turnis true, we will draw X, else we will draw O and change the value of turn. So, first click we draw X andturn becomes false. So, on the second click, we draw O and turn becomes true and so on..

Calculate Winner

Now, after every call in the draw function, we have to calculate if the game is finished or not. If finished, we can find who is the winner and display it.

We will declare three variables more in the data section.

Calculate Tie

Now we will define tie function. The logic is even if there is an empty block, the game is not tied.

Entire script section till now.

Reset Board

Now, when the game is tied or over, we have to show an option to reset the board.

Github code till now.
GitHub - nilmadhab/tic-tac-toe-youtube at game-logic-implemented

Multiplayer mode Using Socket.io

Now, we will integrate the project with Socket.io, so that two players can play the game at the same time. When one player clicks X, it should appear on the second player’s screen and when the second player clicks O, it should appear on the first player’s screen. How to implement it?

Here, socket.IO comes handy. The documentation says,

If you want to watch the video tutorial, you can download the above branch and fast forward the video to 35:42 mins.

Set up server for socket.io

We will first create a folder outside the Vue project. Create a file server.js inside the folder. We will create an express server inside the folder.

Run npm init. It will set apackage.json file.

Then run

npm i socket.io

It will install socket.io in the project.

server.js

Now. lets create a server and integrate socket.io.

We will emit an event from the server and our Vue client should listen to it and receive it.

Run the server with

node server.js

App.vue

Now, we will set up socket.io in client side.

Run

npm i socket.io-client

inside the vue.js project from terminal.

We will import the library by

import io from ‘socket.io-client’
const socket = io(“[http://localhost:3000](http://localhost:3000)")

inside the script section.

In the created hook, we will listen to the event.

You will see “youtube tutorial” will appear in the console.

The client can also talk to the server in the same way.

Game Logic with Socket.io

1. After we call the draw function, player 1 client will send the event to the server.

2. When the server receives it, it will broadcast it to the player 2.

3. Player 2 will then update the grid.

4. Then player 2 will click O and call the draw function, it will send the event to the server.

5. The server will broadcast it to player 1.

The game will keep going like this.

Now, we will update the template. We will send the drawFromOtheras false, which means the event will be sent to the server.

Complete code of App.vue