seothemes

Markdown Editor replaces the default WordPress editor with a Markdown editor for your posts and pages. This plugin uses the Jetpack Markdown module for converting Markdown into HTML and plays nicely with Jetpack if both plugins are installed.
There are 4 editor layouts to choose from when writing posts: default, preview, full-screen and split screen. Changes are updated automatically allowing you to preview your content as you write.
By default Markdown Editor is only enabled on Posts, but you can enable it on pages and custom post types by adding post type support. For example to add Markdown support to Pages, add the following line of code to your theme’s functions.php file:
<pre><code>add_post_type_support( 'page', 'wpcom-markdown' );
</code></pre>
To add Markdown support to a ‘Product’ custom post type, add this to your theme’s functions.php file:
<pre><code>add_post_type_support( 'product', 'wpcom-markdown' );
</code></pre>
<h3>Syntax Highlighting</h3>
By default, Markdown Editor enables syntax highlighting for code blocks. This can be removed by adding the following line of code to your theme’s functions.php file:
<pre><code>add_filter( 'markdown_editor_highlight', '__return_false' );
</code></pre>
The click to copy button can be removed with the following line:
<pre><code>add_filter( 'markdown_editor_clipboard', '__return_false' );
</code></pre>

Markdown Editor

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Kills WordPress

Replaces the default WordPress editor with a Markdown editor for your posts and pages.

Terry L.

Generation of diagrams and flowcharts from text in a similar manner as markdown by using <a href="https://mermaid.js.org/" rel="nofollow ugc">mermaid.js</a>
WP Mermaid is smart enough that loads mermaid.js only when your posts contain Mermaid syntax, by detecting the use of shortcode and block. So it will not be loaded on your website everywhere.
= See also
If you are looking for a <a href="https://github.com/terrylinooo/githuber-md" rel="nofollow ugc">Markdown editor</a> supporting Mermaid, you can also check out my WordPress plugin called the <a href="https://wordpress.org/plugins/wp-githuber-md/" rel="ugc">WP Githuber MD</a>, which provides a variety of features not just Mermaid, it is worth to try.
<h3>Translations</h3>
Chinese (zh_TW) by <a href="https://terryl.in/" rel="nofollow ugc">Terry L.</a>. 
Japanese (ja_JP) by <a href="https://colocal.com/" rel="nofollow ugc">Colocal</a>.
<h3>Copyright</h3>
WP Mermaid, Copyright 2020 TerryL.in 
WP Mermaid is distributed under the terms of the GNU GPL
This program is free software: you can redistribute it and/or modify 
it under the terms of the GNU General Public License as published by 
the Free Software Foundation, either version 3 of the License, or 
(at your option) any later version.
This program is distributed in the hope that it will be useful, 
but WITHOUT ANY WARRANTY; without even the implied warranty of 
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 
GNU General Public License for more details.

WP Mermaid

Generation of diagrams and flowcharts from text in a similar manner as markdown by using mermaid.js

Markdown Editor vs WP Mermaid