markdown-viewer

Markdown Viewer / Chrome Extension

Install

Features

• No special permissions required for file URLs
• Full control over the allowed origins
• Supports multiple markdown parsers
• Full control over the compiler options (marked or showdown)
• Themes support (including GitHub theme) (jasonm23, mixu, cobalt)
• Supports GitHub Flavored Markdown
• Syntax highlighted code blocks (prism)
• Generates Table of Contents (TOC)
• Remembers scroll position
• Settings synchronization
• Raw and rendered markdown views
• Open source

Local Files

1. Navigate to chrome://extensions
2. Make sure that the Allow access to file URLs checkbox is checked for the Markdown Viewer extension

Remote Files

1. Click on the Markdown Viewer icon and select Options
2. Add the origin that you want enabled for the Markdown Viewer extension

Compiler Options

Marked

Option	Default	Description
gfm	true	Enable GFM GitHub Flavored Markdown.
tables	true	Enable GFM tables. This option requires the gfm option to be true.
breaks	false	Enable GFM line breaks. This option requires the gfm option to be true.
pedantic	false	Conform to obscure parts of markdown.pl as much as possible. Don't fix any of the original markdown bugs or poor behavior.
sanitize	false	Sanitize the output. Ignore any HTML that has been input.
smartLists	false	Use smarter list behavior than the original markdown. May eventually be default with the old behavior moved into pedantic.
smartypants	false	Use "smart" typograhic punctuation for things like quotes and dashes.

Showdown

Option	Default	Description
disableForced4SpacesIndentedSublists	true	Disables the requirement of indenting nested sublists by 4 spaces
encodeEmails	true	Encode e-mail addresses through the use of Character Entities, transforming ASCII e-mail addresses into its equivalent decimal entities
excludeTrailingPunctuationFromURLs	true	Excludes trailing punctuation from links generated with autoLinking
ghCodeBlocks	true	Turn on/off GFM fenced code blocks support
ghCompatibleHeaderId	true	Generate header ids compatible with github style (spaces are replaced with dashes, a bunch of non alphanumeric chars are removed)
ghMentions	true	Enables github @mentions
headerLevelStart	false	The header blocks level start
literalMidWordUnderscores	true	Parse midword underscores as literal underscores
noHeaderId	false	Turn on/off generated header id
omitExtraWLInCodeBlocks	true	Omit the default extra whiteline added to code blocks
parseImgDimensions	false	Turn on/off image dimension parsing
prefixHeaderId	false	Specify a prefix to generated header ids
requireSpaceBeforeHeadingText	true	Makes adding a space between # and the header text mandatory (GFM Style)
simpleLineBreaks	true	Parses simple line breaks as (GFM Style)
simplifiedAutoLink	true	Turn on/off GFM autolink style
smartIndentationFix	false	Tries to smartly fix indentation in es6 strings
smoothLivePreview	false	Prevents weird effects in live previews due to incomplete input
strikethrough	true	Turn on/off strikethrough support
tables	true	Turn on/off tables support
tablesHeaderId	true	Add an id to table headers
tasklists	true	Turn on/off GFM tasklist support

Content Options

Option	Default	Description
scroll	true	Remember scroll position
toc	false	Generate Table of Contents

Enable the scroll option while you are working on a markdown document and you are frequently refreshing the page. Also useful when you are reading long document and you want to continue from where you left off.

Disable the scroll option if you want the page rendered at the top or scrolled down to a certain header if a hash URL fragment is present.

Advanced Options

Markdown Viewer doesn't require any specific permissions in order to render markdown files from local file URLs. For example the file:///home/s/chrome/markdown-viewer/README.md on my hard drive will always be rendered without a problem.

Add Origin

In case you want the extension to render markdown files from web URLs you have to specify the server's origin. The origin consists of protocol and domain. You can choouse either https, http or a * for both protocols.

For example here is how you can enable the extension for the https://raw.githubusercontent.com origin:

After that you can navigate to this URL and play around with the compiler options.

Add All Origins

In case you really want to you can enable the extension for all origins:

Specify Path RegExp

By default the extension renders only URLs ending with a markdown file extension:

It's a really simple regular expression that matches URLs ending in .md or .md#some-header. It also uses non capturing groups (?:)

You can change this regular expression to whatever suits your needs. The settings are being updated as you type.

Remove Origin

At any point click on the small x button next to the origin that you want to remove. This actually removes the permission itself so that the extension is no longer able to inject scripts to that origin.

Note that the Chrome's consent popup shows up only when you add the origin for the first time. In case you re-add it you'll no longer see that popup. That's a Chrome thing and it's not controllable from the extension.

Refresh Origin

The extension synchronizes your preferences across all your devices using Google Sync. The list of your allowed origins is being synced too, but the actual permissions that you give using the Chrome's consent popup are not being synced.

In case you recently added a new origin on one of your devices you'll have to explicitly allow it on your other devices. The little refresh button next to each origin is used for that.

Markdown Syntax

• Add the raw.githubusercontent.com origin through the Advanced Options
• Navigate to this URL and play around with the Compiler Options
• Use the Markdown/HTML button to switch between raw markdown and rendered HTML
• At any point click on the Defaults button to reset back the compiler options

License

The MIT License (MIT)

Copyright (c) 2013-2017 Simeon Velichkov [email protected]

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.