Comment Syntax Support

About 3 min...

You can use many syntax in your comment, including expanded Markdown syntax and HTML tags.

Markdown Support

We support full Markdown syntax and the following extensions.

GFM Markdown Favor

Delete lines

This is deleted.

This is ~~deleted~~.
For center align use :-:For right align use -:For left align use :-
|           center           |                    right | left                    |
| :------------------------: | -----------------------: | :---------------------- |
| For center align use `:-:` | For right align use `-:` | For left align use `:-` |
|             b              |                aaaaaaaaa | aaaa                    |
|             c              |                     aaaa | a                       |

Superscript and Subscript

Use ^ and ~ to mark the superscript and subscript.

  • 19th
  • H2O
- 19^th^
- H~2~O


Besides user-configured or built-in Weibo emojis, we also support complete Emoji shorthand emoticons.


😃 😦 😄 😆 😊 😃 😏 😍 😘

:) :( :smile: :laughing: :blush: :smiley: :smirk: :heart_eyes: :kissing_heart:

Code Block Highlight

We support highlighting in almost all languages.

<!DOCTYPE html>
<html lang="en">
      // Just a lil’ script to show off that inline JS gets highlighted
      window.console && console.log('foo');
    <meta charset="utf-8" />
    <link rel="icon" href="assets/favicon.png" />
    <link rel="stylesheet" href="assets/style.css" />
    <link rel="stylesheet" href="themes/prism.css" data-noprefix />
    <script src="assets/vendor/prefixfree.min.js"></script>

      var _gaq = [['_setAccount', 'UA-33746269-1'], ['_trackPageview']];
    <script src="" async></script>
/** @deprecated Use `Prism.plugins.fileHighlight.highlight` instead. */
Prism.fileHighlight = function () {
  if (!logged) {
      'Prism.fileHighlight is deprecated. Use `Prism.plugins.fileHighlight.highlight` instead.'
    logged = true;
  Prism.plugins.fileHighlight.highlight.apply(this, arguments);
@import url(;
@import url(;

@font-face {
  src: url(;
  font-family: 'LeaVerou';

 Shared styles

section h1,
#features li strong,
header h2,
footer p {
  font: 100% Rockwell, Arvo, serif;

Mathematical formula

You can use $ ... $ to create inline formulas, or use $$ ... $$ to create block-level formulas.


Euler’s identity eiπ+1=0e^{i\pi}+1=0 is a beautiful formula in R2\mathbb{R}^2.

Euler’s identity $e^{i\pi}+1=0$ is a beautiful formula in $\mathbb{R}^2$.

rωr(yωω)=(yωω){(logy)r+i=1r(1)ir(ri+1)(logy)riωi}\frac {\partial^r} {\partial \omega^r} \left(\frac {y^{\omega}} {\omega}\right) = \left(\frac {y^{\omega}} {\omega}\right) \left\{(\log y)^r + \sum_{i=1}^r \frac {(-1)^i r \cdots (r-i+1) (\log y)^{r-i}} {\omega^i} \right\}

\frac {\partial^r} {\partial \omega^r} \left(\frac {y^{\omega}} {\omega}\right)
= \left(\frac {y^{\omega}} {\omega}\right) \left\{(\log y)^r + \sum_{i=1}^r \frac {(-1)^i r \cdots (r-i+1) (\log y)^{r-i}} {\omega^i} \right\}

Embed HTML

Feel free to add any HTML content unless triggering the protection mechanism below.


Spam protection

  • To prevent users from creating submitable forms in the comment area to trick other visitors submitting information, <form> and <input> are not allowed

  • To prevent users from using style tag to revise website pages or modify their own comment styles to implant spam ads, the <style> tag and the style attribute are not allowed.

  • To prevent users from abusing media autoplay feature, autoplay attribute is not allowed.

XSS prevention

  • We use DOMPurifyopen in new window to sanitize every comment input to prevent potential XSS attacks. This means you can't use <iframe> or any form of script.

  • All links will be automatically set rel="noreferrer noopener" and opened in a new window with target="_ blank".

Restricted preview function

In order to control the size of @waline/client on client side, we only provides a simple Markdown parser in client side, so many syntax can correctly rendered in the comment area, but they cannot be displayed correctly in the preview panel.

This includes the following restrictions:

  • Standard emoji syntax (e.g.: tada: :tada:) cannot be rendered correctly

  • Superscript and subscript (e.g.: H~2~O, x^2^) cannot be rendered correctly

  • Tex syntax, or mathematical formulas (e.g.: $a = 1$) cannot be rendered correctly by default

    You can set Tex rendering during preview by setting the texRenderer option.

  • Code blocks will be highlighted in random colors splited by specific characters


  1. Considering the size, the client uses marked for rendering and a < 1kb highlighter, which will have the above limitations.

  2. When a user submits a comment, the client embeds custom Emoji images, and the raw comment will be sent to the server.

  3. The server receives the comment, uses markdown-it to render markdown correctly with related plugins, and uses prismjs to highlight code blocks according to the language, then render Tex according to users' settings, and finally executes XSS sanitizing.

  4. After successfully processed, the server storage the render content in database, and returns it to the client when needed so comment will be displayed normally.

TIPS: The comment area is only for demo. If you have any questions, please go to Github Discussion to ask.
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