This is from Sept 2010, so it seems a bit outdated.
For my site, I've been using the code [1] which powers the StackOverflow editor and it works great. It would be pretty easy to set that code up in a page like this one above and you'd get buttons for making things bold, which seems handy.
For Mac there's actually Mou which is super pretty and just like this. It's in beta and free for now but it's Lion-only and one of the 2 reasons I upgraded. It's that good. It's at mouapp.com. Thanks for the Linux tip, I could use that one.
I didn't attach a license to this as:
a) the front-end is just a very simple UI put on top of attacklab.net's showdown.js. Unfortunately, attacklab seems to be dead now but the showdown code has a BSD license, see: http://static.joncom.be/screen/script/showdown.js.
b) the back-end simply opens and saves text files, I didn't think anyone would want to see that.
In answer to your question, attacklab did the hard work and yes there is an open source license attached to his/her work.
If you find this interesting, you might like Pandoc (see http://johnmacfarlane.net/pandoc/try ). That's a "try it online" page, not quite meant for online authoring but could be made to be. Also available as a standalone utility app and a (haskell) library. I've found this works well, and I love the selection of input/output formats.
This might be a shameless plug, but I have created a javascript markdown editor a few months ago. I had some problems with the wmd editor (weird quirks and bugs) and generally wanted to play around with js. So, uedit[0] was born. You can use the demo page[1] to see it in action. It works in ie6+ and doesn't require any other js libraries.
List items are added automatically and you can use shortcuts for the most frequently used markdown tags such as bold, italic, code listing, images etc. It also uses it's own undo/redo manager for more granular control.
Nice idea and impressive implementation. Me and a friend of mine are currently working on something comparable to this demo. We focus on UX and interoperability; our goal is to show it to HN before the end of January.
In markdown, you need to precede the <enter> with two spaces to get a <br>.
As I understand it, Markdown syntax was inspired by email syntax, so we have > for block quotations, * for unordered list items, etc. By this reasoning, a single newline may just be the email client wrapping the text, whereas a double newline means the writer is starting a new paragraph.
Initially I wrote it against the Daring Fireball spec but switched it over to track the output of the showdown javascript library.
Markdown is not a great language to implement. I wrote a hand parser because there are loads of places where you have to look ahead more than one token (not that I am a great lexer/parser expert).
In markdown single line endings are ignored when the lines broken by them might be construed as forming a single paragraph. (It's actually one of the fiddliest bits of markdown.)
This rule is quirky -- sometimes you'll end up with (for example) bullet points merged into a paragraph through this quirk.
This is from Sept 2010, so it seems a bit outdated.
For my site, I've been using the code [1] which powers the StackOverflow editor and it works great. It would be pretty easy to set that code up in a page like this one above and you'd get buttons for making things bold, which seems handy.
[1] http://code.google.com/p/pagedown/