Possible feature: front matter support

[bradparker]

I've got a very specific fork over here: https://github.com/bradparker/markdownify.

It's breaking because the result of requiring a markdown file is now an object rather than a string. It'd be possible to add as an opt-in feature if you think it's worthwhile. If you'd like to add it I can put in the work, just want to know if you're into the idea first :).

Thanks for the super useful transform by the by :).

[prollynomial]

Hey there! I'm not actually familiar with the gray-matter package, would you mind explaining what you see the use case as?

I haven't worked on this project for a few years, but I'd have no problem adding things to it if you feel there's added value in adding gray-matter support.

[bradparker]

Sorry for the delay. Gray matter is a front matter parser. So when you require a markdown file into your bundle you can not only get the parsed content but also some meta-data.

---
date: "2016-03-01",
author: "An Author"
---

#An article

With **markdown** content

Produces:

{
  "orig":"...original content string",
  "data": {
    "date": "2016-03-01",
    "author": "An Author"
  },
  "content": "<h1>An Article</p>\\n\\n<p>With <strong>markdown</strong> content</p>\\n"
}

Original content key could perhaps be removed... might not be all that useful and just blow out bundle size.

Gray matter's pretty handy as your front matter can be in either YAML (as above) or JSON.

In order to optionally add it, options would have to passible to markdownify. Something like:

var markdownify = require('markdownify');
//...
bundler.transform(markdownify({ frontMatter: true }));
// OR no config:
bundler.transform(markdownify());

Perhaps?

Otherwise the current API could be maintained by using the same config API that babelify uses?

bundler.transform(markdownify);
// OR
bundler.transform(markdownify.configure({ frontMatter: true }));

[prollynomial]

Thanks for the explanation - seems cool! If you want to write this and file a pull request I'm sure we can get that in there.

If gray-matter supports files that have no front matter, I have no problem having that enabled at all times, unless you think people are likely to want to turn off.