Clipboard

Adds a copy-to-clipboard button to every code block in posts, plus an optional language label in the top-right. Seven visual themes to choose from.

Ported to Flarum 2.0 from ffans/clipboardjs (MIT). Credit to Golden for the original.

What it does

Two features:

1. Copy button on code blocks — when a visitor hovers over a <pre> in a post, a small "copy" button appears. Click it; the code is on their clipboard. The button briefly flips to a checkmark to confirm. Seven button styles to match the look of GitHub, CSDN, Jianshu, etc.
2. Language label on code blocks — when a syntax highlighter (Prism, highlight.js, etc.) decorates <code> with a language-X class, the extension hoists that class onto the parent <pre> and the CSS shows the language name in the top-right of the block.

Both features have independent toggles in the admin settings; you can use one without the other.

Requirements

• Flarum 2.0 or later
• PHP 8.2 or later
• Optional: a syntax highlighter extension (for the language label feature to have something to display)

Settings

• Enable copy button on code blocks — turn the copy button on or off
• Copy button style — default, GitHub, LingCoder, CSDN, cnBlogs, Jian Shu, SegmentFault
• Show language label on code blocks — turn the language label on or off

How it works under the hood

The extension extends CommentPost.oncreate and, after each post renders, walks the post DOM for <pre> elements. For each one not already decorated, it inserts a themed button. Click handlers use the modern native navigator.clipboard.writeText() API to copy code text, with a hidden-textarea + document.execCommand('copy') fallback for older browsers or non-secure contexts.

The language detection sets up a MutationObserver once per page that watches <code> elements for a language-X class. When one appears (after a syntax highlighter runs), the class is mirrored onto the parent <pre> so the CSS selectors in _languages.less can display the language name.

What changed from the 1.x original

• Targets flarum/core ^2.0
• Renamed namespace: linkrobins-clipboard.*
• Dropped the clipboard npm dependency — modern browsers have a native clipboard API, and the original library is now obsolete
• Dropped the SaveSettings listener — it used Flarum\Api\Event\Serializing which was removed in Flarum 2.0, and its work is redundant with the serializeToForum extender calls already in extend.php
• No webpack/JSX build — vanilla JS, hand-written, no node_modules
• Uses app.registry.for('linkrobins-clipboard') (the 2.0 name) instead of app.extensionData.for(...)
• Setting type renamed switch → boolean (both work; boolean is the modern name)
• CSS class renamed to LinkRobinsClipboard (the .clipboard button class stays the same so themes from upstream still apply)