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    @marp-team/marp-core
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    3.2.1 • Public • Published

    @marp-team/marp-core

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    The core of Marp converter.

    In order to use on Marp tools, we have extended from the slide deck framework Marpit. You can use the practical Markdown syntax, advanced features, and official themes.

    Install

    # npm
    npm install --save @marp-team/marp-core
    # yarn
    yarn add @marp-team/marp-core

    Usage

    We provide Marp class, that is inherited from Marpit.

    import { Marp } from '@marp-team/marp-core'
    
    // Convert Markdown slide deck into HTML and CSS
    const marp = new Marp()
    const { html, css } = marp.render('# Hello, marp-core!')

    Features

    We will only explain features extended in marp-core. Please refer to Marpit framework if you want to know the basic features.


    Marp Markdown

    Marp Markdown is a custom Markdown flavor based on Marpit and CommonMark. Following are principle differences from the original:

    • CommonMark
      • For making secure, we will deny most of HTML tags used in Markdown (<br> is only allowed by default).
      • Support table and strikethrough syntax, based on GitHub Flavored Markdown.
      • Line breaks in paragraph will convert to <br> tag.

    Built-in official themes

    We provide bulit-in official themes for Marp. See more details in themes.

    Default Gaia Uncover
    <!-- theme: default --> <!-- theme: gaia --> <!-- theme: uncover -->

    size global directive

    Do you want a traditional 4:3 slide size? Marp Core adds the support of size global directive. The extended theming system can switch the slide size easier.

    ---
    theme: gaia
    size: 4:3
    ---
    
    # A traditional 4:3 slide

    Bulit-in themes for Marp have provided 16:9 (1280x720) and 4:3 (960x720) preset sizes.

    Define size presets in custom theme CSS

    If you want to use more size presets in your own theme, you have to define @size metadata(s) in theme CSS. Learn in the document of theme metadata for Marp Core.

    Theme author does not have to worry an unintended design being used with unexpected slide size because user only can use pre-defined presets by author.


    Emoji support

    Emoji shortcode (like :smile:) and Unicode emoji 😄 will convert into the SVG vector image provided by twemoji 😄. It could render emoji with high resolution.


    Math typesetting

    We have Pandoc's Markdown style math typesetting support. Surround your formula by $...$ to render math as inline, and $$...$$ to render as block.

    Markdown Rendered slide
    Render inline math such as $ax^2+bc+c$.
    
    $$ I_{xx}=\int\int_Ry^2f(x,y)\cdot{}dydx $$
    
    $$
    f(x) = \int_{-\infty}^\infty
        \hat f(\xi)\,e^{2 \pi i \xi x}
        \,d\xi
    $$

    Math typesetting support

    You can choose using library for math from MathJax and KaTeX in math global directive (or JS constructor option). By default, we prefer MathJax for better rendering and syntax support, but KaTeX is faster rendering if you had a lot of formulas.

    math global directive

    Through math global directive, Marp Core is supporting to declare math library that will be used within current Markdown.

    Set mathjax or katex in the math global directive like this:

    ---
    # Declare to use KaTeX in this Markdown
    math: katex
    ---
    
    $$
    \begin{align}
    x &= 1+1 \tag{1} \\
      &= 2
    \end{align}
    $$

    If not declared, Marp Core will use MathJax to render math. But we recommend to declare the library whenever to use math typesetting.

    ⚠️ The declaration of math library is given priority over math JS constructor option, but you cannot turn on again via math global directive if disabled math typesetting by the constructor.


    Auto-scaling features

    Marp Core has some auto-scaling features:

    Auto-scaling is available if defined @auto-scaling metadata in an using theme CSS.

    /*
     * @theme foobar
     * @auto-scaling true
     */

    All of Marp Core's built-in themes are ready to use full-featured auto scalings. If you're the theme author, you can control target elements which enable auto-scaling by using metadata keyword(s).

    This feature depends to inline SVG, so note that it will not working if disabled Marpit's inlineSVG mode by setting inlineSVG: false in constructor option.

    ⚠️ Auto-scaling is designed for horizontal scaling. In vertical, the scaled element still may stick out from top and bottom of slide if there are a lot of contents around it.

    Fitting header

    When the headings contains <!-- fit --> comment, the size of headings will resize to fit onto the slide size.

    # <!-- fit --> Fitting header

    This syntax is similar to Deckset's [fit] keyword, but we use HTML comment to hide a fit keyword on Markdown rendered as document.

    Auto-shrink the block

    Some of blocks will be shrunk to fit onto the slide. It is useful preventing stuck out the block from the right of the slide.

    Traditional rendering Auto-scaling
    Code block Traditional rendering Auto-scaling
    KaTeX math block Traditional rendering Auto-scaling

    ℹ️ MathJax math block will always be scaled without even setting @auto-scaling metadata.


    Constructor options

    You can customize a behavior of Marp parser by passing an options object to the constructor. You can also pass together with Marpit constructor options.

    ℹ️ Marpit's markdown option is accepted only object options because of always using CommonMark.

    const marp = new Marp({
      // marp-core constructor options
      html: true,
      emoji: {
        shortcode: true,
        unicode: false,
        twemoji: {
          base: '/resources/twemoji/',
        },
      },
      math: 'katex',
      minifyCSS: true,
      script: {
        source: 'cdn',
        nonce: 'xxxxxxxxxxxxxxx',
      },
    
      // It can be included Marpit constructor options
      looseYAML: false,
      markdown: {
        breaks: false,
      },
    })

    html: boolean | object

    Setting whether to render raw HTML in Markdown. It's an alias to markdown.html (markdown-it option) but has additional feature about HTML allowlist.

    • true: The all HTML will be allowed.
    • false: All HTML except supported in Marpit Markdown will be disallowed.

    By passing object, you can set the allowlist to specify allowed tags and attributes.

    // Specify tag name as key, and attributes to allow as string array.
    {
      a: ['href', 'target'],
      br: [],
    }
    // You may use custom attribute sanitizer by passing object.
    {
      img: {
        src: (value) => (value.startsWith('https://') ? value : '')
      }
    }

    Marp core allows only <br> tag by default, that is defined in Marp.html.

    Whatever any option is selected, <!-- HTML comment --> and <style> tags are always parsed by Marpit for directives / tweaking style.

    emoji: object

    Setting about emoji conversions.

    • shortcode: boolean | "twemoji"
      • By setting false, it does not convert any emoji shortcodes.
      • By setting true, it converts emoji shortcodes into Unicode emoji. :dog:🐶
      • By setting "twemoji" string, it converts into twemoji vector image. :dog:🐶 (default)
    • unicode: boolean | "twemoji"
      • It can convert Unicode emoji into twemoji when setting "twemoji". 🐶🐶 (default)
      • If you not want this aggressive conversion, please set false.

    For developers: When you setting unicode option as true, Markdown parser will convert Unicode emoji into tokens internally. The rendering result is same as in false.

    math: boolean | "mathjax" | "katex" | object

    Enable or disable math typesetting syntax and math global directive.

    You can choose the default library for math by passing "mathjax" (default) or "katex", and modify more settings by passing an object of sub-options.

    • lib: "mathjax" | "katex"
      • Choose the default library for math typesetting. (mathjax by default)
    • katexOption: object
      • Options that will be passed to KaTeX. Please refer to KaTeX document.
    • katexFontPath: string | false
      • By default, Marp Core will use online web-font resources through jsDelivr CDN. You have to set path to fonts directory if you want to use local resources. If you set false, we will not manipulate the path (Use KaTeX's original path: fonts/KaTeX_***-***.woff2).

    minifyCSS: boolean

    Enable or disable minification for rendered CSS. true by default.

    script: boolean | object

    Setting about an injected helper script for the browser context. This script is necessary for applying WebKit polyfill and rendering auto-scaled elements correctly.

    • true: Inject the inline helper script into after the last of slides. (default)
    • false: Not inject helper script. Developer must execute a helper script manually, exported in @marp-team/marp-core/browser. Requires bundler such as webpack. It's suitable to the fully-controlled tool such as Marp Web.

    You can control details of behavior by passing object.

    • source: string - Choose the kind of script.
      • inline: Inject the inline script. It would work correctly also in the environment that there is not network. (default)
      • cdn: Inject script referred through jsDelivr CDN. It's better choice on the restricted environment by CSP.

    Contributing

    Are you interested in contributing? Please see CONTRIBUTING.md and the common contributing guideline for Marp team.

    Author

    Managed by @marp-team.

    License

    This package releases under the MIT License.

    Install

    npm i @marp-team/marp-core

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    Version

    3.2.1

    License

    MIT

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    Collaborators

    • yhatt