Example of upload application. The server is made with Koa js (https://koajs.com/) and
use aws-sdk package. The main component is in src/components/Uploads. The src/S3PostUploader.jsx component
is builded component from yarn build (removed flow types) and copied here to example for usage.
$ yarn
As first set correctly awsConfig credentials (accessKeyId, secretAccessKey, ...) in
server.js file.
Execute yarn start-example. The server with react application will be started.
