This script no longer works and is no longer supported. See the Stack Overflow Extras (SOX) for this functionality.


editor on the left, preview on the right


This userscript adds a button to the editor toolbar ('Toggle Side-By-Side Editing') so you can view the preview and markdown side by side when asking or answering a question or when editing an existing question or answer.


After installing Greasemonkey in Firefox or Tampermonkey in Chrome, click here.


This userscript was originally adapted from a bookmarklet by ˈjuː.zɚ79365 by ᔕᖺᘎᕊ. Since then Antonio Vargas has made some contributions to it as well.


Almost all of the reformatting is done using CSS with jQuery's toggleClass().

For more detail check out the source code on GitHub.

Please post bugs/feature-requests as answers over here. I'll try my best to fix/add them!

  • I loaded this on one computer a few months ago and it's great. I tried to load it on another computer several times over the last few days and get a 404 error from the download link.
    – fixer1234
    Commented Apr 23, 2016 at 17:13
  • @fixer1234 weird.. it's still there! You can install Stack Overflow Extras (SOX) instead, which contains this feature as well as a bunch of other features! It's also been updated since I posted this, so should be less buggy! :) Commented Apr 24, 2016 at 18:22
  • Thanks, I'll check that out. BTW, the problem might be a dependency or incorrect link. The actual error message is "Error downloading URL: gist/github.com/raw/2625891/waitForKeyElements.js"
    – fixer1234
    Commented Apr 24, 2016 at 18:57
  • @fixer1234 ah yes, I see the problem. I've updated the script. Could you try reinstalling that? (btw I've replied to that comment on GH! Thanks for trying it and sorry for the problems you have! I'll try my best to get them sorted!) Commented Apr 24, 2016 at 20:19
  • SOX is quite a work of art. I'm not sure it has enough features though. :-) Any chance the two side-by-side editing issues are related? Any potential conflict or interaction between this standalone script and the side-by-side feature of SOX?
    – fixer1234
    Commented Apr 24, 2016 at 21:27
  • I retested this script on the same installation as SOX. At first, I thought it wasn't working, but it worked on two questions, and one out of two answers. This is the answer it didn't work on if it helps: [Windows default font in bars? [duplicate]](superuser.com/a/1069262/364367). (Didn't work = no "button" for side-by-side editing).
    – fixer1234
    Commented Apr 24, 2016 at 23:00
  • 1
    Hi @ᔕᖺᘎᕊ, this script: no longer seems to work and hasn't been updated in a few years. Plus you seem to be steering people to SOX. Should we mark this post as obsolete or do you intend to update the script shortly? Commented Jan 18, 2019 at 1:27
  • @Brock you're right -- I can mark it as obsolete or mark it as a dupe of SOX, which do you think it better? :) Commented Jan 18, 2019 at 7:22
  • 1
    I'm leaning towards the latter because of this and I know how annoying it is to arrive at a promising page and be told that the princess is in another castle... If you really want it closed as a dupe instead, roll back the edit. Commented Jan 18, 2019 at 7:40

1 Answer 1


I've updated the description to reflect the new version of the userscript.

New features in 1.1

  • Side by side editing can be used when editing existing questions or answers.
  • Can be toggled on and off by clicking the new button again.
  • When turned on the editor is stretched to the current length of the preview.
  • Bug: this doesn't work when I am editing posts. It only works when I am posting new posts.
    – caveman
    Commented Jun 1, 2016 at 1:28
  • @caveman that's been fixed in SOX, which contains this feature and many others :) Commented Aug 28, 2016 at 15:12
  • 1
    Its still not working (unable to edit existing post with this option on) Commented Nov 23, 2018 at 10:07

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