Here is a couple of changes to add a COPY TO CLIPBOARD feature for Discourse code blocks.

Install it directly as a mini-Theme via:

https://github.com/daemonite/discourse-clipboard

Or you can manually apply this feature to a Discourse forum as follows:

  • Go to “Admin” setting page and then select “Customize” in the top nav
  • Create a new theme or select an existing one in the left-hand column and then click on the “Edit CSS/HTML” button
  • Copy the following code and paste it into CSS and </head> sections of the selected theme respectively:

CSS

// A copy of the functions used to determine the background colour of the code block
// https://github.com/discourse/discourse/blob/3dcad123f5a7cf0de3c4a57554a752b96a214943/app/assets/stylesheets/common/foundation/variables.scss
@function brightness($color) {
  @return ((red($color) * .299) + (green($color) * .587) + (blue($color) * .114));
}

@function dark-light-choose($light-theme-result, $dark-theme-result) {
  @if brightness($primary) < brightness($secondary) {
    @return $light-theme-result;
  } @else {
    @return $dark-theme-result;
  }
}

// CSS for clipboard
.bd-clipboard {
  background-color: dark-light-choose(#f8f8f8, #333333);
  display: block;
  position: relative;
  text-align: right;
  text-align: end;
  white-space: nowrap;
}

.bd-clipboard + pre {
  margin-top: 0;
}

.btn-clipboard {
  background-color: transparent;
  border-radius: 2px;
  color: dark-light-choose(#333333, #f8f8f8);
  cursor: default;
  display: inline-block;
  font-size: .857142857em;
  padding: 0.25em 0.4em;
}

.btn-clipboard:hover {
  background-color: $tertiary;
  color: $secondary;
}

</head>

<!-- JavaScript for clipboard -->
<script type="text/discourse-plugin" version="0.8">
/*!
 * clipboard.js v2.0.0
 * https://zenorocha.github.io/clipboard.js
 * 
 * Licensed MIT © Zeno Rocha
 */
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</script>

<script type="text/discourse-plugin" version="0.8">
  api.decorateCooked(
    $elem => $('pre', $elem).each(function () {
      if ($(this).parent('.code-highlight').length === 1) {
        return;
      }

      // Add copy button to code block
      $(this).wrap('<div class="code-highlight"></div>').before('<div class="bd-clipboard"><span class="btn-clipboard">Copy</span></div>')
      
      // Initialise clipboard
      var clipboard = new ClipboardJS('.btn-clipboard', {
        target: function (trigger) {
          return trigger.parentNode.nextElementSibling
        }
      })
    
      // Update text of the copy button
      clipboard.on('error', function (e) {
        var modifierKey = /Mac/i.test(navigator.userAgent) ? '\u2318' : 'Ctrl-'
        var fallbackMsg = 'Press ' + modifierKey + 'C to copy'
        
        $(e.trigger).text(fallbackMsg)
      })
      
      clipboard.on('success', function (e) {
        $(e.trigger).text('Copied!')
        e.clearSelection()
      })
    })
  )

  // Revert back text of the copy button
  $(document).on('mouseleave', '.btn-clipboard', function () {
    $(this).text('Copy')
  })
</script>

Note, Discourse uses ember.js for internal navigation, so the DOM will only be ready once. This plugin ties up the clipboard function with ember.js via Discourse APIs, so the code runs when the content of a post is cooked instead of on DOM ready .

Related Topics

https://meta.discourse.org/t/add-button-to-select-all-text-in-a-preformatted-block/30878

Thanks to our “Material Master” Maya at Daemon for this mini Theme hack :slight_smile:
https://labs.daemon.com.au/t/copy-option-for-code-blocks-in-discourse/279