Try this if you are facing issues while using web3JS in ReactJS

Uncaught ReferenceError: process is not defined

If you are getting this error right after importing the Web3js package in your ReactJs application then you are using create-react-app version >=5 for this reason you may run into issues building. This is because NodeJS polyfills are not included in the latest version of create-react-app.

SOLUTION:

Step1:

If you are using yarn:

yarn add --dev react-app-rewired process crypto-browserify stream-browserify assert stream-http https-browserify os-browserify url buffer

If you are using npm:

npm install --save-dev react-app-rewired crypto-browserify stream-browserify assert stream-http https-browserify os-browserify url buffer process

STEP2:

Create config-overrides.js in the root of your project folder with the content:

const webpack = require('webpack');

module.exports = function override(config) {
    const fallback = config.resolve.fallback || {};
    Object.assign(fallback, {
        "crypto": require.resolve("crypto-browserify"),
        "stream": require.resolve("stream-browserify"),
        "assert": require.resolve("assert"),
        "http": require.resolve("stream-http"),
        "https": require.resolve("https-browserify"),
        "os": require.resolve("os-browserify"),
        "url": require.resolve("url")
    })
    config.resolve.fallback = fallback;
    config.plugins = (config.plugins || []).concat([
        new webpack.ProvidePlugin({
            process: 'process/browser',
            Buffer: ['buffer', 'Buffer']
        })
    ])
    return config;
}

Step3:

Within package.json change the scripts field for start, build and test. Instead of react-scripts replace it with react-app-rewired.

Change your scripts from this:

"scripts": {
    "start": "react-scripts start",
    "build": "react-scripts build",
    "test": "react-scripts test",
    "eject": "react-scripts eject"
},

TO THIS :

"scripts": {
    "start": "react-app-rewired start",
    "build": "react-app-rewired build",
    "test": "react-app-rewired test",
    "eject": "react-scripts eject"
},

Conclusion:

That is it now you can use web3js package in your ReactJs Application. you can also view offlical web3js Github repo: (github.com/ChainSafe/web3.js/tree/v1.7.4)