README?

[jhult]

A brief README explaining how to use would be helpful.

[Soreine]

@quentez your library and https://github.com/lever/planer/ seems identical in terms of features, and they are both ported from Mailgun/Talon. Why did you chose to make your own port when planer existed already ?
Is there a reason to choose one over the other ?

The only thing I noticed is that talonjs is quite faster than planer, maybe because you're using XMLDom instead of JSDom, even if you also use cheerio to cleanup and convert the HTML document to XML.