Showdown HTML Escape plugin

This plugin for Showdown prevents the use of arbitrary HTML and allows only the specific Markdown syntax.

This is useful if you want to allow your users to format text using the Markdown syntax but you do not want them to directly enter HTML.

Installation

With bower

bower install showdown-htmlescape

With npm

npm install showdown-htmlescape

Manual

You can also download the latest release zip or tarball and include the file dist/showdown-htmlescape.js directly in your project.

Enabling the extension

Browser

You have to include both Showdown and the Showdown HTML Escape extension in your project:

<script src="showdown.min.js"></script>
<script src="showdown-htmlescape.min.js"></script>

After including the extension in your application, you just need to enable it for your Showdown converter:

var converter = new showdown.Converter({extensions: ['htmlescape']})

Node.js

var showdown = require('showdown')
var showdownHtmlEscape = require('showdown-htmlescape')
var converter = new showdown.Converter({ extensions: [showdownHtmlEscape] })

Usage example

var converter = new showdown.Converter({extensions: ['htmlescape']})
var input = 'Allows **Markdown markup**, but does not allow <b>HTML markup</b>'
var html = converter.makeHtml(input)
console.log(html)

This should output:

<p>Allows <strong>Markdown markup</strong>, but does not allow &lt;b&gt;HTML markup&lt;/b&gt;</p>

Notes on security

This plugin is not meant to protect you from XSS attacks, it justs limits the syntax available to the user to the Markdown specific syntax. If security and XSS prevention is important for your use case you still must filter the HTML generated by Showdown. See Markdown's XSS Vulnerability (and how to mitigate it) for details.

License

Published under the MIT license, see LICENSE.txt for details.

phw/showdown-htmlescape