npm run dev
npm run build
need some edit 😔
1️⃣ replace src path in out/ directory "/_next -> "/spring/_next"
2️⃣ create .nojekyll file in out/
see https://github.com/zeit/next.js/wiki/Deploying-a-Next.js-app-into-GitHub-Pages
3️⃣ 🚀
npm run deploy