Don't work in simple browser

[ProgrammeurZero]

When write:
var asciidoctor = Asciidoctor()
my console tell me that `Asciidoctor is undefined'.

[ggrossetie]

Asciidoctor.js is most likely not correctly set up.

Please direct usage questions to the chat first: https://chat.asciidoctor.org. If we determine there is a bug, then we can proceed with a new issue. This helps us to better maintain the project.

Thanks.