Home | Legacy Firefox Extensions | Content Policy | Contact

Regex Find


Adds a Regex checkbox to the findbar.
This allows to search text on page using regular expressions.

---------------------- Note For Firefox 57+ ---------------------------
New WebExtensions standard of addons development is currently restrictive for this extension
and prevents it from being updated to support the newer browser versions in the release channel.
But the Nightly branch has more freedom in this sense. So here is a tutorial to use this addon in the Firefox Nightly 57+: Install Legacy Addons in Firefox Nightly 57+.

In short:
  - backup your Default profile (User\AppData\Roaming\Firefox\Profiles\___.default)
  - install Nightly (nightly.mozilla.org or http://ftp.mozilla.org/pub/firefox/nightly/)
  - create new profile for the Nightly version
  - allow legacy addons: load URL 'about:config?filter=extensions.legacy.enabled', set it to true
  - allow unsigned addons: load URL 'about:config?filter=xpinstall.signatures.required', set it to false
  - install the addon, enable it in the Add-ons Manager
  - if the addon doesn't work try it in the non-multiprocess mode (File - New Non-e10s Window,
    or Options-uncheck 'Enable multi-process Nightly',
    or load URL 'about:config?filter=browser.tabs.remote.autostart' and set it to false
---------------------- End Note For Firefox 57+ -----------------------

The maximum supported Firefox version for this addon is Firefox 56.
Newer browser versions' standards are not compatible with the source code.

It is possible to install the addon in Firefox Nightly 57+ using the direct release from GitHub. Available links:
    - direct installation: regex-find.xpi
    - all releases: https://github.com/mortalis13/Regex-Find/releases
    - source code: https://github.com/mortalis13/Regex-Find

You may click on the direct link and allow the installation or download the XPI file to your PC and drag it to the browser for manual installation.
To download it right click on the link and select 'Save Link As...'.

If you have any question or problem installing it create an issue on GitHub using the Support Site link on this page.

The addon offers basic regex search functionality with these limitations:
- some Regex control symbols - \f, \r, \n, \v
- by default doesn't search in dynamically loaded content
- doesn't support lookbehind search because it's not implemented in Javascript

1. To search dynamic content (AJAX added text, when hidden elements become visible) it's necessary to reload the regex search (uncheck/check) the Regex button, so the addon will rescan the page text with all its current content.

2. In Firefox Nightly 57+ the search should be used in a non-multiprocess window in which the addon will have access to browser internal objects needed to perform the page text scanning and search. To open this type of window go to File - New Non-e10s Window. It's also possible to disable multiprocess behavior for the whole browser in the Options - Enable multi-process Nightly, the any pages will support the Regex search.

3. F2 shortcut can be used for backward search.

New versioning from v1.2.1

As the addon behaviour is different in some Firefox versions I tried to create addon versions covering browser version ranges to be compatible with them.
So on the versions page of the addon you can see 3 rows (it's in the Version History section below):
- 1.2.1-45 - for Firefox 45-49
- 1.2.1-50 - for Firefox 50-54
- 1.2.1-55 - for Firefox 55-56


Version 1.1.6:
- search in input elements (input, textarea)
- search in iframe elements
- search in button elements
- search after page reload

Version 1.1.7:
- support for versions 45-49

Version 1.1.8:
- support for versions 55-56

Version 1.2.0:
- prevent force search field focus on findAgain
- focus inputs when selecting found text
- support for searching in dynamically changed inputs

Download files:


This page is part of the LegacyCollector website.
Disclaimer: All material on this site is property of their respective owners and available under
open licenses to the best of our knowledge. If you are an author and would like anything removed,
then please write an e-mail to legacy [at] collector dot org.