Marked-sanitizer-github NPM

Port of GitHub's Markdown Sanitizer for marked

marked-sanitizer-github provides a sanitizer to sanitize HTML elements in Markdown documents. The implementation was ported from html-pipeline.

marked provides sanitization by default. But it does not allow any HTML elements and escapes all of them in a parsing Markdown document. By using marked-sanitizer-github, some safe HTML elements are available.

When a sanitizer detects broken HTML elements (e.g. not closing element), it escapes all elements after that.

This package was created to be used for Shiba.

Installation

$ npm install --save marked-sanitizer-github

Usage

It exports one class SanitizeState because the sanitization is stateful. You can get a sanitizer for marked parser by calling getSanitizer() method. It returns a function object to sanitize.

const marked = require('marked');
const SanitizeState = require('marked-sanitizer-github').default;

const md = `some document`;

const state = new SanitizeState();

// Convert a markdown document to HTML with sanitization
const html = marked(md, {
    sanitize: true,
    sanitizer: state.getSanitizer(),
});

console.log(html);

SanitizeState class also provides reset() method, isBroken() method and isInUse() method.

reset() method resets the sanitization state. If you use the SanitizeState object multiple times, you must call the method before parsing a markdown document.

isBroken() method returns whether the state is broken. A broken state means that Some HTML elements in a sanitized document were broken (e.g. tag mismatch, closing tag does not appear, ...).

You can have a callback to know the reason why the document is broken as follows:

state.onDetectedBroken = (reason, tag) => {
    console.error(`Broken HTML around '${tag}' tag: ${reason}`);
};

isInUse() method returns whether the state object has ongoing state or is ready for parsing a new document. true means the internal state is in use (not ready for parsing a new document). Returning true means it requires to call reset() method before parsing a new document.

Sanitized elements

Allowed elements: h1, h2, h3, h4, h5, h6, h7, h8, br, b, i, strong, em, a, pre, code, img, tt, div, ins, del, sup, sub, p, ol, ul, table, thead, tbody, tfoot, blockquote, dl, dt, dd, kbd, q, samp, var, hr, ruby, rt, rp, li, tr, td, th, s, strike, summary and details
Allowed attributes: Only following attributes are allowed for allowed elements.
- a: href
- img: src and longdesc
- div: itemscope and itemtype
- blockquote: cite
- del: cite
- ins: cite
- q: cite
- ALL: abbr, accept, accept-charset, accesskey, action, align, alt, axis, border, cellpadding, cellspacing, char, charoff, charset, checked, clear, cols, colspan, color, compact, coords, datetime, dir, disabled, enctype, for, frame, headers, height, hreflang, hspace, ismap, label, lang, maxlength, media, method, multiple, name, nohref, noshade, nowrap, open, prompt, readonly, rel, rev, rows, rowspan, rules, scope, selected, shape, size, span, start, summary, tabindex, target, title, type, usemap, valign, value, vspace, width and itemprop
Allowed protocols in attributes: Only following protocols are allowed as values of allowed attributes
- a:
  - href: http, https, mailto, github-windows and github-mac
- blockquote:
  - cite: http and https
- del:
  - cite: http and https
- ins:
  - cite: http and https
- q:
  - cite: http and https
- img:
  - src: http and https
  - longdesc: http and https
li must be nested in ul and ol
Table items (tr, td and th) and table headers (thead, tbody and tfoot) must be nested in table