Undocumented npm.compilers

[borowskiio]

I was getting 'import' or "'export' should appear at the top level" error and struggled to solve it until I found some github issue that explained to use npm.compilers options... which are undocumented and unexplained.

[Jesspu]

This is still undocumented on the website, and in the brunch guide.

There are actually a few things that need better, or some sort of documentation. The brunch guide seems better than the site, but still missing things like npm compilers.