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Extension retirement

Firefox 57, to be released November 14, 2017, will remove support for the Firefox Add-ons SDK -- upon which this extension is built -- in favor of the WebExtensions API. That is to say, fascr will soon cease to work, starting with Firefox 57.

Unfortunately, I do not have time to port fascr to the new API. However, the WebExtensions API is based on Chrome's extension API, so someone mildly tech-savvy should be able to package reasonable to work with Firefox.

  • bdhr


fascr (For a site called Reason) is a Firefox extension with functionality similar to brymck's excellent Chrome extension reasonable (though the two share no common code).

Current features

  • Block and "mute" users Posts by blocked posters and replies to them will disappear completely, as if they had never existed. Posts by muted posters, in contrast, will have only their content hidden (with option to temporarily display), with byline and reply preserved.
  • "Toggle" top-level threads When a conversation does not interest you, you can hide a thread by clicking "toggle" next to a top-level post. This will persist across refreshes without affecting other posts by that user.
  • Highlight posts by a certain user (e.g., you)
  • Highlight unread posts
  • Navigate with hotkeys Press shift-alt-j to move forward through unread posts, shift-alt-k to move back
  • Count characters typed Note that it is actually bytes that are counted, because it appears that this is what Reason's limit is actually based on.

New in 0.7.xx

  • HTML tag buttons Common HTML tags can be inserted via buttons above comment boxes. If text is highlighted, the tags will surround the highlighted text; otherwise, an empty pair of tags will be placed at the current cursor position. a corresponds to links (place the URL between the double quotation marks), em to italics, strong to bolded text, and s to struck text.
  • Inline alt text alt and/or title attributes are displayed as / concatenated to image captions, where applicable. Especially useful on mobile.
  • Optional 'mark-read-on-advance' mode See below for a more detailed description

Editing blocklist / mutelist

To remove users from your blocklist, click on your username to the right of the Reason logo where it says "You are currently logged in as: [handle]". fascr will insert lists of all currently blocked and muted posters on that page; click on them to remove them.

Mark-read-on-advance Mode

The "classic" behavior of fascr and its Chrome equivalent reasonable is to treat all comments as unread when an article is first viewed, and thereafter, to mark them as read upon its next viewing. This is still the default behavior, and logical for most Android devices, which usually lack keyboards.

This behavior is straightforward and easy to implement, but irritating if you would like reply to a comment midway through reviewing the unread comments.

I have implemented a new behavior which can be enabled by selecting "Mark individual post as read when reached via hotkey" as the value of the option "Unread post tracking behavior".

With this option enabled, posts made after the first time you view an article will not be marked as read until you either reach them via hotkeys (as a reminder, shift-alt-j to move forwards and shift-alt-k to move backwards) or mark all as read at once using shift-alt-m -- even if you comment or refresh.

This way, you will never "lose your place" by making a comment.



  • Download the XPI file
  • Open the Add-ons menu in Firefox (click the "hamburger menu" [the three horizontal lines in the upper right] to reveal the button to access it)
  • Next to the box that says "Search all add-ons", there is a button with a gear icon. Click it.
  • Click "Install Add-on From File..."
  • Select the XPI file you downloaded.
  • Click "Install"

Mobile (Android)

  • Go here to install on Android for some arcane reasons

Usage notes / tips & known issues

  • Performance will be much better with an ad-blocking mechanism in place. Please donate to Reason instead.
  • Hotkeys will not work until the page is completely loaded.
  • If a thread is toggled, clicking "Block" adds its poster to the blocklist, but does not remove the post. Un-toggling the thread rectifies the issue.
  • Hotkeys sometimes don't work. This appears to be a Firefox Add-ons SDK bug.


The extension itself is distributed under the MIT license. Font Awesome is licensed under the MIT license and the OFL 1.1.

Contact me