deno-gfm

Server-side GitHub Flavored Markdown rendering for Deno, including GitHub style CSS, syntax highlighting, and HTML sanitization.

Usage

import { CSS, render } from "https://deno.land/x/gfm/mod.ts";

const markdown = `
# Hello, world!

| Type | Value |
| ---- | ----- |
| x    | 42    |

\`\`\`js
console.log("Hello, world!");
\`\`\`
`;

const body = render(markdown, {
  baseUrl: "https://example.com",
});

const html = `
<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <style>
      main {
        max-width: 800px;
        margin: 0 auto;
      }
      ${CSS}
    </style>
  </head>
  <body>
    <main data-color-mode="light" data-light-theme="light" data-dark-theme="dark" class="markdown-body">
      ${body}
    </main>
  </body>
</html>
`;

Styling

The GitHub CSS styles (https://primer.style) are used. There are two themes available: light and dark.

There are three data attributes that can be used to control the theme:

data-color-mode: light or dark or auto.
data-light-theme: the name of the light theme (light or dark).
data-dark-theme: the name of the dark theme (light or dark).

For example, if you want to use the dark theme only, set the following:

<div data-color-mode="dark" data-dark-theme="dark" class="markdown-body">
  ... markdown body here ...
</div>

If you want to use the light or dark theme depending on the user’s browser preference, set the following:

<div data-color-mode="auto" data-light-theme="light" data-dark-theme="dark" class="markdown-body">
  ... markdown body here ...
</div>

Also see the example application in the example/ directory.

Extensibility

By default syntax highlighting for JavaScript, Markdown, and HTML is included. You can include more languages importing them:

import { CSS, render } from "https://deno.land/x/gfm/mod.ts";

// Add support for TypeScript, Bash, and Rust.
import "https://esm.sh/prismjs@1.29.0/components/prism-typescript?no-check";
import "https://esm.sh/prismjs@1.29.0/components/prism-bash?no-check";
import "https://esm.sh/prismjs@1.29.0/components/prism-rust?no-check";

A full list of supported languages is available here: https://unpkg.com/browse/prismjs@1.29.0/components/

Inline rendering

By default, all rendering is in blocks. There are cases where one would like to render some inline markdown, and this is achievable using the inline setting:

import { render } from "https://deno.land/x/gfm/mod.ts";

const markdown = "My [Deno](https://deno.land) Blog";
const header = render(markdown, { inline: true });
console.log(header);

Math rendering

By default math rendering is disabled. To enable it, you must include the additional CSS and enable the allowMath setting:

import { CSS, KATEX_CSS, render } from "https://deno.land/x/gfm/mod.ts";

const markdown = `
Block math:

<span class="katex-display"><span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML" display="block"><semantics><mrow><mi>y</mi><mo>=</mo><msup><mi>x</mi><mn>2</mn></msup></mrow><annotation encoding="application/x-tex">y = x^2</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.625em;vertical-align:-0.1944em;"></span><span class="mord mathnormal" style="margin-right:0.03588em;">y</span><span class="mspace" style="margin-right:0.2778em;"></span><span class="mrel">=</span><span class="mspace" style="margin-right:0.2778em;"></span></span><span class="base"><span class="strut" style="height:0.8641em;"></span><span class="mord"><span class="mord mathnormal">x</span><span class="msupsub"><span class="vlist-t"><span class="vlist-r"><span class="vlist" style="height:0.8641em;"><span style="top:-3.113em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight">2</span></span></span></span></span></span></span></span></span></span></span></span>

Inline math: <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>y</mi><mo>=</mo><msup><mi>x</mi><mn>2</mn></msup></mrow><annotation encoding="application/x-tex">y = x^2</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.625em;vertical-align:-0.1944em;"></span><span class="mord mathnormal" style="margin-right:0.03588em;">y</span><span class="mspace" style="margin-right:0.2778em;"></span><span class="mrel">=</span><span class="mspace" style="margin-right:0.2778em;"></span></span><span class="base"><span class="strut" style="height:0.8141em;"></span><span class="mord"><span class="mord mathnormal">x</span><span class="msupsub"><span class="vlist-t"><span class="vlist-r"><span class="vlist" style="height:0.8141em;"><span style="top:-3.063em;margin-right:0.05em;"><span class="pstrut" style="height:2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight">2</span></span></span></span></span></span></span></span></span></span></span>
`;

const body = render(markdown, {
  allowMath: true,
});

const html = `
<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <style>
      main {
        max-width: 800px;
        margin: 0 auto;
      }
      ${CSS}
      ${KATEX_CSS}
    </style>
  </head>
  <body>
    <main data-color-mode="light" data-light-theme="light" data-dark-theme="dark" class="markdown-body">
      ${body}
    </main>
  </body>
</html>
`;