Download the example or clone the repo:

curl https://codeload.github.com/zeit/next.js/tar.gz/master | tar -xz --strip=2 next.js-master/examples/with-babel-macros
cd with-babel-macros

Install it and run:

npm install
npm run dev

Deploy it to the cloud with now (download)

now

This example features how to configure and use babel-macros which allows you to easily add babel plugins which export themselves as a macro without needing to configure them.

You'll notice the configuration in .babelrc includes the babel-macros plugin, then we can use the preval.macro in pages/index.js to pre-evaluate code at build-time. preval.macro is effectively transforming our code, but we didn't have to configure it to make that happen!

Specifically what we're doing is we're prevaling the username of the user who ran the build.