Create a Coin Flipping App using ReactJS

In this article, we will build a coin flipping application. In which the user can flip a coin and get a random result from head or tails. We create three components ‘App’ and ‘FlipCoin’ and ‘Coin’. The app component renders a single FlipCoin component only. FlipCoin component contains all the behind the logic. It has a default prop coin that is an array that contains two images head and tail (sides of a coin). It is a stateful component. The handler function also keeps track of how many times the flip button is clicked and how many times the head face generated randomly and updates its value to the respective state.

Let us have a look at how the final application will look like:

 Coin Flipping App using ReactJS

Prerequisites:

• React
• Stateful Components

Steps to create application:

Step 1: Create the project file using command

npx create-react-app flip

Step 2: Navigate to the folder using the command

cd flip

Step 3: Create the folder components and inside the folder create two files FlipCoin.js and Coin.js

After following the above steps the project structure will look like:

Project Structure

The dependencies in package.json will look like:

package.json:

"dependencies": {
    "@testing-library/jest-dom": "^5.16.5",
    "@testing-library/react": "^13.4.0",
    "@testing-library/user-event": "^13.5.0",
    "react": "^18.2.0",
    "react-dom": "^18.2.0",
    "react-scripts": "5.0.1",
    "web-vitals": "^2.1.4"
}

Example:

• App.js: App component renders single FlipCoin component only 
• FlipCoin.js: It contains all the behind logic. It is a stateful component. The states are currFace, totalFlips, and heads.It is responsible for Setting event handler, updating all the states according to the user interaction render Coin component.
• Coin.js: Responsible to show a side of a coin according to the currFace state of FlipCoin component. FlipCoin component communicates with the Coin component through the props system

Javascript

// App.js

import React from 'react';
import FlipCoin from './components/FlipCoin'

const App=()=> {
  return (
    <div className="App">
      <FlipCoin />
    </div>
  );
}

export default App;

Javascript

// FlipCoin.js

import React, { Component } from 'react'
import Coin from './Coin'

class FlipCoin extends Component {
    static defaultProps = {
        coins: [
            // Sides of the coin
            {
                side: 'head',
                imgSrc:
'https://media.geeksforgeeks.org/wp-content/uploads/20200916123059/SHalfDollarObverse2016head-300x300.jpg'
            },
            {
                side: 'tail',
                imgSrc:
'https://media.geeksforgeeks.org/wp-content/uploads/20200916123125/tails-200x200.jpg'
            }
        ]
    }

    constructor(props) {
        super(props)
        // Responsible to render current updated coin face
        this.state = {
            // Track total number of flips
            currFace: null,
            totalFlips: 0,
            heads: 0
        }
        // Binding context of this keyword
        this.handleClick = this.handleClick.bind(this)
    }

    // Function takes array of different faces of a coin
    //  and return a random chosen single face
    choice(arr) {
        const randomIdx = Math.floor(Math.random() * arr.length)
        return arr[randomIdx]
    }

    // Function responsible to update the states
    // according to users interactions
    flipCoin() {
        const newFace = this.choice(this.props.coins)
        this.setState(curState => {
            const heads = curState.heads +
                (newFace.side === 'head' ? 1 : 0)
            return {
                currFace: newFace,
                totalFlips: curState.totalFlips + 1,
                heads: heads
            }
        })
    }
    handleClick() {
        this.flipCoin()
    }
    render() {
        const { currFace, totalFlips, heads } = this.state
        return (
            <div>
                <h2>Let's flip a coin</h2>
                {/* If current face exist then show current face */}
                {currFace && <Coin info={currFace} />}
                {/* Button to flip the coin  */}
                <button onClick={this.handleClick}>Flip Me!</button>
                <p>
                    Out of {totalFlips} flips, there have been {heads} heads
                    and {totalFlips - heads} tails
                </p>
            </div>
        )
    }
}

export default FlipCoin

Javascript

// Coin.js

import React, { Component } from 'react'

class Coin extends Component {
    render() {
        return (
            <div class='Coin'>
                <img
                    style={{ width: '200px', height: '200px' }}
                    src={this.props.info.imgSrc}
                />
            </div>
        )
    }
}

export default Coin

Steps to run the applicaton:

Step 1: Type the following command in terminal

npm start

Step 2: Open web browser and type the following URL

http://localhost:3000/

Output :

 Coin Flipping App using ReactJS