This PayPal Checkout integration uses the PayPal JavaScript SDK released in February 2019.
Before developing code, make sure you get PayPal REST API credentials from the Developer Portal.
In the file PaypalButton.js, replace 'YOUR_CLIENT_ID' with your REST API credentials. See the documentation for customizing the SDK for a complete list of query parameters and values.
After cloning or downloading the project files, go to the project directory and run this command:
npm install
This will install all packages required to run the projects, as well as any packages that they depend on. This step may take a few minutes to finish.
To run the project, use this command in the project directory:
npm start
A browser tab will open. If that doesn't happen, open http://localhost:3000 to view it in the browser.