12 KiB
<zero-md>
Ridiculously simple zero-config markdown displayer
A native markdown-to-html web component based on Custom Elements V1 specs to load and display an external MD file. Under the hood, it uses Marked for super-fast markdown transformation, and Prism for feature-packed syntax highlighting - automagically rendering into its own self-contained shadow DOM container, while encapsulating implementation details into one embarassingly easy-to-use package.
NOTE: This is the V2 branch. If you're looking for the older version, see the V1 branch.
Featuring:
- Automated hash-link scrolls
- Built-in FOUC prevention
- Automatically rewrite URLs relative to
src
- Automatically re-render when
src
changes - Automatically re-render when inline markdown or style template changes
- Support for >200 code languages with detection for unhinted code blocks
- Easy styling mechanism
- Highly extensible
Documentation: https://zerodevx.github.io/zero-md/
NOTE: Your markdown file(s) needs to be hosted! Browsers don't generally allow javascript to access files on the local hard drive because of security concerns. Standard CORS rules apply.
Installation
Load via CDN (recommended)
zero-md
is designed to be zero-config with good defaults. For most use-cases, just importing the
script from CDN and consuming the component directly should suffice.
<head>
...
<!-- Import element definition -->
<script
type="module"
src="https://cdn.jsdelivr.net/gh/zerodevx/zero-md@2/dist/zero-md.min.js"
></script>
...
</head>
<body>
...
<!-- Profit! -->
<zero-md src="/example.md"></zero-md>
...
</body>
Latest stable: https://cdn.jsdelivr.net/gh/zerodevx/zero-md@2/dist/zero-md.min.js
Latest beta: https://cdn.jsdelivr.net/npm/zero-md@next/dist/zero-md.min.js
Install in web projects
Install package with npm
or yarn
. Note that you'll need Node.js
installed.
$ npm install --save zero-md
Import the class, register the element, and use anywhere.
// Import the element definition
import ZeroMd from 'zero-md'
// Register the custom element
customElements.define('zero-md', ZeroMd)
// Render anywhere
app.render(`<zero-md src=${src}></zero-md>`, target)
Or load the distribution directly in HTML.
<script type="module" src="/node_modules/zero-md/dist/zero-md.min.js"></script>
...
<zero-md src="example.md"></zero-md>
Basic Usage
Display an external markdown file
<!-- Simply set the `src` attribute and win -->
<zero-md src="https://example.com/markdown.md"></zero-md>
At its most basic, <zero-md>
loads and displays an external MD file with default stylesheets -
a Github-themed stylesheet paired with a light-themed one for code blocks, just like what you see in
these docs. So internally, the above code block is semantically equivalent to the one below:
<zero-md src="https://example.com/markdown.md">
<!-- By default, this style template gets loaded -->
<template>
<link
rel="stylesheet"
href="https://cdn.jsdelivr.net/gh/sindresorhus/github-markdown-css@4/github-markdown.min.css"
/>
<link
rel="stylesheet"
href="https://cdn.jsdelivr.net/gh/PrismJS/prism@1/themes/prism.min.css"
/>
</template>
</zero-md>
Using your own styles
To override the default theme, supply your own style template.
<zero-md src="https://example.com/markdown.md">
<!-- Wrap with a <template> tag -->
<template>
<!-- Define your own styles inside a `<style>` tag -->
<style>
h1 {
color: red;
}
...;
</style>
</template>
</zero-md>
Or your own stylesheets
<zero-md src="https://example.com/markdown.md">
<!-- Wrap with a <template> tag -->
<template>
<!-- Load external stylesheets with a `<link rel="stylesheet">` tag -->
<link rel="stylesheet" href="markdown-styles.css" />
<link rel="stylesheet" href="highlight-styles.css" />
</template>
</zero-md>
Or both
<zero-md src="https://example.com/markdown.md">
<template>
<!-- The CSS load order is respected -->
<link rel="stylesheet" href="markdown-styles.css" />
<style>
h1 {
color: red;
}
</style>
<link rel="stylesheet" href="highlight-styles.css" />
<style>
code {
background: yellow;
}
</style>
</template>
</zero-md>
Write markdown inline
You can pass in your markdown inline too.
<!-- Do not set the `src` attribute -->
<zero-md>
<!-- Write your markdown inside a `<script type="text/markdown">` tag -->
<script type="text/markdown">
# **This** is my [markdown](https://example.com)
</script>
</zero-md>
By default, <zero-md>
first tries to render src
. If src
is falsy (undefined, file not found,
empty file etc), it falls-back to the contents inside the <script type="text/markdown">
tag.
Put it all together
<zero-md src="https://example.com/markdown.md">
<template>
<link rel="stylesheet" href="markdown-styles.css" />
<style>
h1 {
color: red;
}
</style>
<link rel="stylesheet" href="highlight-styles.css" />
<style>
code {
background: yellow;
}
</style>
</template>
<script type="text/markdown">
This is the fall-back markdown that will **only show** when `src` is falsy.
</script>
</zero-md>
API
Advanced usage: https://zerodevx.github.io/zero-md/advanced-usage/
Attributes and helpers: https://zerodevx.github.io/zero-md/attributes-and-helpers/
Configuration: https://zerodevx.github.io/zero-md/configuration/
Migrating from V1 to V2
- Support for
<xmp>
tag is removed; use<script type="text/markdown">
instead.
<!-- Previous -->
<zero-md>
<template>
<xmp>
# `This` is my [markdown](example.md)
</xmp>
</template>
</zero-md>
<!-- Now -->
<zero-md>
<!-- No need to wrap with <template> tag -->
<script type="text/markdown">
# `This` is my [markdown](example.md)
</script>
</zero-md>
<!-- If you need your code to be pretty, -->
<zero-md>
<!-- Set `data-dedent` to opt-in to dedent the text during render -->
<script type="text/markdown" data-dedent>
# It is important to be pretty
So having spacing makes me happy.
</script>
</zero-md>
- Markdown source behaviour has changed. Think of
<script type="text/markdown">
as a "fallback".
<!-- Previous -->
<zero-md src="will-not-render.md">
<template>
<xmp>
# This has first priority and will be rendered instead of `will-not-render.md`
</xmp>
</template>
<zero-md>
<!-- Now -->
<zero-md src="will-render-unless-falsy.md">
<script type="text/markdown">
# This will NOT be rendered _unless_ `src` resolves to falsy
</script>
</zero-md>
- The
css-urls
attribute is deprecated. Use<link rel="stylesheet">
instead.
<!-- Previous -->
<zero-md src="example.md" css-urls='["/style1.css", "/style2.css"]'><zero-md>
<!-- Now, this... -->
<zero-md src="example.md"></zero-md>
<!-- ...is actually equivalent to this -->
<zero-md src="example.md">
<template>
<!-- These are the default stylesheets -->
<link
rel="stylesheet"
href="https://cdn.jsdelivr.net/gh/sindresorhus/github-markdown-css@4/github-markdown.min.css"
/>
<link
rel="stylesheet"
href="https://cdn.jsdelivr.net/gh/PrismJS/prism@1/themes/prism.min.css"
/>
</template>
</zero-md>
<!-- So, to apply your own external stylesheets... -->
<zero-md src="example.md">
<!-- ...you overwrite the default template -->
<template>
<!-- Use <link> tags to reference your own stylesheets -->
<link rel="stylesheet" href="/style1.css" />
<link rel="stylesheet" href="/style2.css" />
<!-- You can even apply additional styles -->
<style>
p {
color: red;
}
</style>
</template>
</zero-md>
<!-- If you like the default stylesheets but wish to apply some overrides -->
<zero-md src="example.md">
<!-- Set `data-merge` to "append" to apply this template AFTER the default template -->
<!-- Or "prepend" to apply this template BEFORE -->
<template data-merge="append">
<style>
p {
color: red;
}
</style>
</template>
</zero-md>
- The attributes
marked-url
andprism-url
are deprecated. To loadmarked
orprism
from another location, simply load their scripts before importingzero-md
.
<head>
...
<script defer src="/lib/marked.js"></script>
<script defer src="/lib/prism.js"></script>
<script type="module" src="/lib/zero-md.min.js"></script>
</head>
- The global config object has been renamed from
ZeroMd.config
toZeroMdConfig
.
<!-- Previous -->
<script src="/node_modules/@webcomponents/webcomponentsjs/webcomponents-loader.js"></script>
<script>
window.ZeroMd = {
config: {
cssUrls: ['/styles/my-markdown-theme.css', '/styles/my-highlight-theme.css']
}
}
</script>
<script
type="module"
src="https://cdn.jsdelivr.net/gh/zerodevx/zero-md@1/src/zero-md.min.js"
></script>
<!-- Now -->
<script>
window.ZeroMdConfig = {
cssUrls: ['/styles/my-markdown-theme.css', '/styles/my-highlight-theme.css']
}
</script>
<script
type="module"
src="https://cdn.jsdelivr.net/gh/zerodevx/zero-md@2/dist/zero-md.min.js"
></script>
- The convenience events
zero-md-marked-ready
andzero-md-prism-ready
are removed and will no longer fire. Instead, thezero-md-ready
event guarantees that everything is ready, and that render can begin.
Contributing
Noticed a bug? Have a feature request?
Open a new issue in the Github repo, or raise a PR! I'd be stoked to accept any contributions!
Development
Standard Github contribution workflow applies.
Run the dev server
$ npm run dev
Point your browser to http://localhost:8000
and you should see the test suite running.
Testing
Tests are browser-based and run on Mocha with
Chai asserts. If you're adding a new feature or bugfixing, please add the
corresponding regression test into test/index.spec.js
accordingly.
Format and lint
$ npm run format
$ npm run lint
Formatting and linting by prettier and eslint respectively.
Making changes to docs
Documentation is in the /docs
folder in the form of readme.md
files, and published on
Github Pages. This setup is based on
zero-md-docs
.
To make changes to docs, simply raise a PR on any readme.md
files should suffice.
Changelog
Check out the releases page.
License
ISC
Acknowledgement
A big thank you to the following contributors and sponsors! 🙏