Carta is a lightweight, fast and extensible Svelte Markdown editor and viewer, based on Marked. Check out the demo to see it in action. Differently from most editors, Carta includes neither ProseMirror nor CodeMirror, allowing for an extremely small bundle size and fast loading time.

Features

• Keyboard shortcuts (extensible);
• Toolbar (extensible);
• Markdown syntax highlighting;
• Scroll sync;
• SSR compatible;
• Katex support (plugin);
• Slash commands (plugin);
• Emojis, with included search (plugin);
• Tikz support(plugin);
• Attachment support(plugin);
• Code blocks syntax highlighting (plugin).

Getting started

Warning

Sanitization is not dealt with by Carta. You need to provide a sanitizer in the options. Common sanitizers are isomorphic-dompurify (suggested) and sanitize-html.

Installation

Core package:

npm i carta-md

Plugins:

npm i @cartamd/plugin-name

Basic configuration

<script lang="ts">
	import { Carta, CartaEditor } from 'carta-md';
	// Component default theme
	import 'carta-md/default-theme.css';
	// Markdown input theme (Speed Highlight)
	import 'carta-md/light.css';

	const carta = new Carta({
		// Remember to use a sanitizer to prevent XSS attacks
		// sanitizer: mySanitizer
	});
</script>

<CartaEditor {carta} />

<style>
	/* Or in global stylesheet */
	/* Set your custom monospace font */
	:global(.carta-font-code) {
		font-family: '...', monospace;
	}
</style>

Editor component exported properties:

Name	Type	Description
carta	Carta	Carta Editor
theme	string	For custom css themes, see below for more
value	string	Markdown input
placeholder	string	Placeholder text for textarea
mode	'tabs' | 'split' | 'auto'	Tabs settings
disableToolbar	boolean	Option to disable the toolbar

Plugins

Each plugin's readme includes a guide on its use.

Name	Description
plugin-math	Katex support
plugin-slash	Slash commands support
plugin-emoji	Emojis support, including inline search
plugin-code	Code blocks syntax highlighting
plugin-tikz	TikZ support using TikZJax
plugin-attachment	Attachments support

Themes customization

By using the theme property in CartaEditor and CartaPreview you can change their classes to carta-editor__{theme} and carta-viewer__{theme}.

Check out the default theme to customize it.

If you are using a plugin, look at its readme for its customization.

Markdown highlighting is done using Speed Highlight JS, here you can find more themes.

You can find complete Markdown stylesheet online. For example github-markdown-css(used in the demo), or tailwind-typography.

Extensibility

Options

Carta options:

Name	Type	Description
extensions	CartaExtension[]	Editor/viewer extensions
rendererDebounce	number	Renderer debouncing timeout, in ms (def. 300ms)
disableShortcuts	DefaultShortcutId[] | true	Remove default shortcuts by ids
disableIcons	DefaultIconId[] | true	Remove default icons by ids
disablePrefixes	DefaultPrefixId[] | true	Remove default prefixes by ids
historyOptions	Partial<CartaHistoryOptions>	History (Undo/Redo) options
sanitizer	(html: string) => string	HTML sanitizer

You can easily extend Carta by creating custom plugins. Here are all the CartaExtension properties:

Name	Type	Description
markedExtensions	marked.MarkedExtension[]	Marked extensions, more on that here
shortcuts	KeyboardShortcut[]	Additional keyboard shortcuts
icons	CartaIcon[]	Additional icons
prefixes	Prefix[]	Additional prefixes
listeners	CartaListener[]	Textarea event listeners
components	CartaExtensionComponents	Additional components, that will be put after the editor. All components are given a carta: Carta. prop The editor has a relative position, so you can position elements absolutely
highlightRules	HighlightRule[]	Custom markdown highlight rules. See Speed-Highlight Wiki.
onLoad	(data: { carta:Carta, ... }) => void	Use this callback to execute code when one Carta instance loads the extension.

If you created a plugin and want to share it, you can open an issue and we will consider sponsoring it on this guide.

Contributions

Every contribution is well accepted. If you have a feature request you can open a new issue.

This package uses a pnpm workspace, so pnpm is required to download and put everything together properly.

Committing

This repository is commitizen friendly. To commit use:

npm run commit
# or, if you have commitizen installed globally
git cz