Marked Documentation

Marked instance

By default, Marked stores options and extensions in the global scope. That means changing the options in one script will also change the options in another script since they share the same instance.

If you don't want to mutate global scope, you can create a new instance of Marked to ensure options and extensions are locally scoped.

import { Marked } from 'marked';
const marked = new Marked([options, extension, ...]);

The parse function

import { marked } from 'marked';
marked.parse(markdownString [,options])

Alternative using reference

// Create reference instance
import { marked } from 'marked';

// Set options
marked.use({
  async: true,
  pedantic: false,
  gfm: true,
});

// Compile
console.log(marked.parse(markdownString));

Options

Known Extensions

Marked can be extended using custom extensions. This is a list of extensions that can be used with marked.use(extension).

Inline Markdown

You can parse inline markdown by running markdown through marked.parseInline.

const blockHtml = marked.parse('**strong** _em_');
console.log(blockHtml); // '<p><strong>strong</strong> <em>em</em></p>'

const inlineHtml = marked.parseInline('**strong** _em_');
console.log(inlineHtml); // '<strong>strong</strong> <em>em</em>'

Highlighting

Use marked-highlight to highlight code blocks.

Workers

To prevent ReDoS attacks you can run marked on a worker and terminate it when parsing takes longer than usual.

Marked can be run in a worker thread on a node server, or a web worker in a browser.

Node Worker Thread

// markedWorker.js

import { marked } from 'marked';
import { parentPort } from 'worker_threads';

parentPort.on('message', (markdownString) => {
  parentPort.postMessage(marked.parse(markdownString));
});

// index.js

import { Worker } from 'worker_threads';
const markedWorker = new Worker('./markedWorker.js');

const markedTimeout = setTimeout(() => {
  markedWorker.terminate();
  throw new Error('Marked took too long!');
}, timeoutLimit);

markedWorker.on('message', (html) => {
  clearTimeout(markedTimeout);
  console.log(html);
  markedWorker.terminate();
});

markedWorker.postMessage(markdownString);

Web Worker

NOTE: Web Workers send the payload from postMessage in an object with the payload in a .data property

// markedWorker.js

importScripts('path/to/marked.min.js');

onmessage = (e) => {
  const markdownString = e.data
  postMessage(marked.parse(markdownString));
};

// script.js

const markedWorker = new Worker('./markedWorker.js');

const markedTimeout = setTimeout(() => {
  markedWorker.terminate();
  throw new Error('Marked took too long!');
}, timeoutLimit);

markedWorker.onmessage = (e) => {
  clearTimeout(markedTimeout);
  const html = e.data;
  console.log(html);
  markedWorker.terminate();
};

markedWorker.postMessage(markdownString);

CLI Extensions

You can use extensions in the CLI by creating a new CLI that imports marked and the marked binary.

// file: myMarked
#!/usr/bin/node

import { marked } from 'marked';
import customHeadingId from 'marked-custom-heading-id';

marked.use(customHeadingId());

import 'marked/bin/marked';

$ ./myMarked -s "# heading {#custom-id}"
<h1 id="custom-id">heading</h1>