> We need a better Markdown previewer.

![travis](https://travis-ci.org/utatti/pen)

pen is a Markdown previewer written in JavaScript, aiming to just work.

There are literally tons of Markdown previewers out there. I love some of them,
I even made one of them. Nevertheless,
we always need a better one, don't we?

Using pen is super simple, we don't need to install any special editor or
launch any GUI application. pen is just a tidy command-line tool. You can use
your favourite editor and browser. No manual refresh is even needed.

Also, the previewer renders the content using React.
It means that it will not re-render entire DOM when the document is updated.
This is a huge advantage because images or other media won't be reloaded for
the DOM update.

I personally love to use pen, and I hope you love it too. :black_nib:

Demo

Here is a short demo showing how awesome pen is.

!demo

The following demo shows pen incrementally updates only modified part using
React and its Reconciliation.

!incremental update

Requirement

pen uses Node.js >= 4.0. It may not work
on earlier versions.

Install

Using npm:

``shell npm i -g pen`

You can try using pen with npx:

`shell npx pen`

`Usage`

To use pen, simply run the pen command.

`shell pen README.md`

The command above will launch a penserver and open the file in your default browser. The server will listen to a 6060 port by default. To be honest, you don't even need to launch it with a filename. You can manually open http://localhost:6060/README.md, or any other files in the same directory.

To stop the server, enter ^C.

For the further details of the pen command, please enter pen -h or pen
--help.

`$3`

Pen uses markdown-it as Markdown parser by default, but it also supports Pandoc. Please provide a proper Pandoc format for the value.

`shell pen --pandoc gfm README.md`

`Contribution`

I welcome every contribution on pen. You may start from forking and cloning this repo.

`shell git clone git@github.com:your_username/pen.git cd pen

`Install dependencies`


npm i
Lint, build, and test pen codes at once

npm test


To build frontend scripts:

`shell npm run build`

To lint with ESLint:

`shell npm run lint`

To test with Mocha

`shell npm run mocha``

License

Pen is released under the MIT License.

Usage

To use pen, simply run the pen command.

shell
pen README.md

The command above will launch a pen

 server and open the file in your default
browser. The server will listen to a 6060 port by default. To be honest, you
don't even need to launch it with a filename. You can manually open
http://localhost:6060/README.md, or any other files in the same directory.

To stop the server, enter ^C.

For the further details of the pen command, please enter pen -h or pen
--help.

$3

Pen uses markdown-it as Markdown
parser by default, but it also supports Pandoc. Please provide a proper Pandoc
format for the value.

shell
pen --pandoc gfm README.md