• Answers will occasionally be moved to the Sandbox archive when there are too many of them. When using them to report bugs, keep an eye on the post.
  • This site, Meta Stack Exchange, is usually used as a "test bed" for pending changes happening to the way text is rendered on all network sites. Changes to text rendering that are going to be rolled out to the network are usually deployed here first to test them out and fix any potential glitches. Currently, there are no such changes pending, but if there were, keep in mind that text posted here may render differently from the other sites until the changes roll out to them as well.

As per Jeff's suggestion in this comment:

You can use this question as a formatting sandbox. You can:

  • edit this question itself (Community Wiki questions such as this one require only 100 reputation to edit instead of 2,000)
  • post answers to this question (This question might be protected, requiring earning 10 reputation on this site to answer)
  • post comments to this question or its answers
  • test suspected bugs with the editor or the rendering
  • post ponies (only when mods are asleep)

Beware that since the changes to syntax highlighting in December 2010, and the inline hints added in March 2011, no syntax highlighting is applied unless the question's tags or an inline hint enable it. So, to test highlighting here in the sandbox:

  1. As of January 8, 2019, you can use GitHub-flavor fenced code blocks in your posts, specifying the language after the opening fence:

    While not hinted otherwise: <html></html> source <b>goes</b> "here".
    var a = 3;
    while (not (a > 0)) {
        alert("JavaScript code <b>goes</b> here.");
  2. Or:

    • Create code blocks in any way (using the fence notation above, the four-space indent form, or using HTML <pre><code> tags).

    • Save your post.

    • Use your browser's developer tools to edit the resulting HTML. To open developer tools, press F12, or ⌥⌘ I on Mac.

    • Find the <pre> element and add the attribute class="prettyprint", or change it into one of the valid syntax hints linked above, like class="lang-vb prettyprint".

    • Run the following in the location bar: javascript:prettyPrint(); or prettyPrint() in the console.

Answers that are considered annoying or obnoxious, or that cause breakage for users, will be deleted. This is codified as a policy as of March 29, 2018.

  • Bold code block.Italic code block. – smileycreations15 Mar 4 '19 at 12:36
  • Is new line working correct? Adding two spaces at the end of this line And now the new line... And another another... No new lines :( – smajli Mar 5 '19 at 11:14
  • New line </br> continue in new line... – smajli Mar 5 '19 at 11:16
  • Test: meta.stackexchange.com/questions/324682/… – Alex Mar 17 '19 at 2:35
  • Do HTML &quot; entities &quot; work&nbsp;? Guess not. – a mask-wearing arachnid Apr 1 '19 at 22:18
  • 6
    A comment with some weird markdown, to test and help this user. Look tags work too, and so does tour. – Bhargav Rao Apr 6 '19 at 1:59
  • 7
    Note: Do not remove @BhargavRao's comment, or you will break this answer – wizzwizz4 Apr 6 '19 at 17:16
  • @BhargavRao When sandbox answers are moved to the archive, comments such as this one -- on the question itself -- aren't migrated; they're deleted. – rgettman Apr 9 '19 at 19:37
  • @rgettman, yeah, that is fine. I had used it for just a small demonstration. The linked answer itself is self-sufficient. Thanks anyway. – Bhargav Rao Apr 9 '19 at 20:22
  • @BringBackThePolyglot Do you get notifications if I reply to your comment and then delete your comment before you visit the site? (for those wondering how I can single-handedly delete someone else's comment, comments containing "thanks" are automatically deleted as soon as someone flags them) – Donald Duck Apr 25 '19 at 16:32
  • @DonaldDuck Yes, I got notified. – Bring Back The Polyglot Apr 25 '19 at 16:32
  • honestly the over 500 hundred upvotes for a sandbox post is taking this real time satire thing you guess do with rep points too far – Adam May 7 '19 at 11:14
  • It makes me feel like doing one too like an onion announcing the Debian contributor community have been assigned complete authority and trust over all encryption matters for the central banks of the world but no, im an adult, I can show restrain – Adam May 7 '19 at 11:16
  • no I'm seriously asking now, what does op mean when someone causes a user "breakage"? is that like the time I was not allowed to take the archer profile pic down for like 6 months? that did break me tbh – Adam May 7 '19 at 11:22
  • help center, help center, help center, help center and help center – link to frequently visited pages of the help center. Link text is "help center" (capitalization is respected). All links point to the main site. – AVK May 16 '19 at 17:45

107 Answers 107


This is my code:

collections: subcategory
    category_name: "ICT",
    subcategory_name: "Laptop"


     "keyup .searchbox": function(event){
           var query = event.target.value;
           Session.set('query', query);

     subcategory: function(){
         var filter = {sort: {}};
         var query = Session.get('query');
         filter.sort[Session.get('sortby')] = 1;
         return Subcategory.find({ subcategory_name: new RegExp(query, 'i')} , filter ); 

  • Comments are used to ask for clarification or to point out problems in the post. Outdated comments may get deleted. Learn more about comments…. – Bring Back The Polyglot Jul 15 at 23:19
  • Comments use mini-Markdown formatting: [link](http://example.com) _italic_ **bold** `code` . The post author will always be notified of your comment. To also notify a previous commenter, mention their user name: @peter or @PeterSmith will both work. Learn more about formatting… – Bring Back The Polyglot Jul 15 at 23:20
  • enter at least 15 characters – Bring Back The Polyglot Jul 15 at 23:25
  • testing how to undo votes on comments – Bring Back The Polyglot Jul 15 at 23:25
  • Apparently if you mess with the Javascript you can undo votes on comments within 60 seconds of voting even after refreshing the page. – Donald Duck Jul 15 at 23:28
  • But it doesn't seem to be possible to undo votes on comments if you voted more than 60 seconds ago, not even by messing with the Javascript. – Donald Duck Jul 15 at 23:31
  • Here is the code to undo votes on comments if you voted less than 60 seconds ago: let machin = document.createElement("form"); machin.method = "post"; machin.action = "/posts/comments/<comment id>/vote/0"; let fkey = document.createElement("input"); fkey.name = "fkey"; fkey.value = "fa360d325887bceb4de2c5522d095a7f65960ee9954efab80223ad4e67b23610"; machin.appendChild(fkey); document.body.appendChild(machin); machin.submit();. Paste it into the developer console on the same site as the comment is on, and replace <comment id> with the ID of the comment you want to undo your vote on. – Donald Duck Jul 15 at 23:33

Dots of shame.

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Testing testing runnable script

document.getElementById("p1").innerHTML = "js"
p {
  color: green;
<a href = "https://www.youtube.com/watch?v=dQw4w9WgXcQ" target = "_blank">Click the link!</a>
<p> :) </p>
<p id = "p1"></p>

| improve this answer | |

Minimal example for HTML comments breaks formatting from that point, but bloated in order to avoid being converted to a comment when I want it to remain as an answer.





Testing a possible bug on mobile web.

This should be rendered as italics (asterisks).
That, as well (underscores).
This is bold text.
Also bold text.

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Formatting quotes. The markdown is this:

> This text is being used as a test.
> The second line is treated as part of the first line.

> The third line is kept separate from the second line, but appears like a new section of quoteblock.
> The fourth line is kept separate from the fourth line, but continues the same quoteblock, but is spaced "far"  from the third line.    [there are four trailing spaces here]
> The fifth line is kept separate from the fourth line, but continues the same quoteblock, but is spaced "close" to the fourth line.

The actual appearance is this:

Formatting quotes.

This text is being used as a test. The second line is treated as part of the first line.

The third line is kept separate from the second line, but appears like a new section of quoteblock.

The fourth line is kept separate from the fourth line, but continues the same quoteblock, but is spaced "far" from the third line.
The fifth line is kept separate from the fourth line, but continues the same quoteblock, but is spaced "close" to the fourth line.

| improve this answer | |
  • 1
    Yeah, the four trailing spaces creating a break like a <br /> tag confused me for the longest time. The lack of a > in the space creating a break in the blockquote is part of the recent switch to CommonMark. – BSMP Sep 5 at 4:44

This is a test to see if the new highlighter handles certain dark corners of shell syntax better than the old one. Code snippet from this old post. YES is a comment, NO isn't.

echo 1 # YES
echo 2 $# NO foo# NO
echo 3;#YES
cat << E
# NO
echo 4 " # NO \" # NO" \" # YES
echo "5
# NO
$(echo 6 # YES
`echo 7 \" # NO \"`
eval 'echo 8 # NO, then YES'
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<script src="https://polyfill.io/v3/polyfill.min.js?features=es6"></script>
<script id="MathJax-script" async src="https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-mml-chtml.js"></script>


The following can only be done by ♦ moderators (and employees who have a diamond):


14: Post Locked - A post was locked by a moderator.
15: Post Unlocked - A post was unlocked by a moderator.
18: Question Merged - A question has had another, deleted question merged into itself.

The following can only be done by ♦ moderators (and employees who have a diamond) on questions:

16: Community Owned - A post has become community owned.
17: Post Migrated - A post was migrated. (Meta Stack Exchange only)

The following cannot be done by ♦ moderators:

  • 17: Post Migrated - A post was migrated. (if older than 60 days)
  • 21: Post Disassociated - An admin removes the OwnerUserId from a post.
  • 22: Question Unmerged - A previously merged question has had its answers and votes restored.

enter image description here

or use an img tag

<img src="https://i.stack.imgur.com/o3JGL.png" />


"Example" domain names that trigger editor warnings:

Hmmm, none of these trigger warnings?!

....not on the meta site, but they do on the main site. BUT not all main sites!


posting sample answer from api [tour]


Placeholder 4️⃣ some tests…





public string X {get; set;}


public string X {get; set;}
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Very good! Fantastic! Very good! Fantastic! Very good! Fantastic!frefferfgerger

This is a test.

Still a test.

  • List item

I keep testing.

Until it breaks.

  • Another list item

    And it doesn't break if you indent by 4 spaces



| improve this answer | |
  • Um... I don't understand what's going on in this answer – mindstormsboi Jun 9 at 13:36
  • 1
    @mindstormsboi Formatting sandbox answers are typically nonsensical. I wouldn't worry about them too much, unless they're Rude/Abusive. – Spevacus Jun 9 at 13:58
  • yeah, just testing things – FireCubez Jun 9 at 14:50

Escaped characters in comments.

| improve this answer | |
  • _/\_ renders like this: _/_ – ChrisW Jun 21 at 7:52
  • _/\\_ renders like this: _/\_ – ChrisW Jun 21 at 7:53

.bold text after a dot works in answers

.it can also be done using HTML tags


<$ ‮ !oboRhceTehT m'I ,iH

Try editing the above sentence post to say something else (but dont remove the <$), you'll have nightmares >:)

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  • Aha! Unicode hacks! ‮‮ – mindstormsboi Jun 30 at 14:00

Hi I keep seeing posts that start with "hi" so I want to check to see if "hi" still gets removed.

Apparently "Hi," or "Hi everyone," gets removed, but just "Hi" without the comma doesn't.


Testing highlighted text links

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Morbi eget nunc sed dui ullamcorper suscipit sit amet vitae arcu. Donec egestas dolor vitae pretium consectetur. Mauris consequat, purus eu dignissim feugiat, dui massa venenatis felis, ut luctus felis felis id nunc. Fusce tristique ultrices mauris bibendum finibus. In hac habitasse platea dictumst. Proin facilisis odio vel vulputate euismod. Quisque finibus a libero eu pulvinar. Aliquam porta urna non neque laoreet, vel malesuada libero efficitur. Donec consectetur tellus in nunc auctor, id feugiat sapien pretium. Sed at metus dui. Sed ipsum metus, interdum nec erat et, tempor feugiat dui. Integer rutrum.

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An answer to the question

In line code span may be nice

function dummy() {
    printf "Dummy gets $p1"
  • How to
    This way
    Besides that way is ok, the other way is quite better
  • Whith what?
    With this and that
  • When?
    Right now

And as Zaratustra in Ein Buch für Alle und Keinen said...

Nicht reden einmal will ich wieder mit dem Volke; zum letzten Male sprach ich zu einem Todten

crystal clear

Some other matters

I love linux and I accept windows...and doors as well
some lines of code

Working code in this rextester

  • Refreshing the syntax/ Tks for this sandbox – Fico Sep 30 at 18:18



Why do you use x in your for loop when the standard is i?


You use the name repeatLoop for one function but sdl_bindings for a class.

Your use of goto makes this code very unreadable

Look up Goto considered harmful

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Just checking inline img tag with svg.

Normal (PNG) image:

PNG inline image:

SVG image:

SVG inline image:


Testing <sup>: 2222222222222222222222222222222

Testing <sub>: 2222222222222222222222222222222

Both mixed:



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Copy this answer and add a new link. Now see that there is now another link with numbered 5.

Is it because of the link descriptions?


  • Message length In Cryptography, usually, the message length is not considered secret. There are approaches that you can add random values to the end or beginning or both if this is really an information leak for you. The random approach depends on your actual data case...

  • The (IV, key) pair reuse problem that can eliminate the confidentiality with the crib-dragging technique.

  • Lack of authentication Like all unauthenticated encryption modes, the bare CTR mode lacks integrity and authentication. A single bit of flipping can have catastrophic results. The AES-GCM mode that used the CTR mode of operation provides you all-in-once, however, it has the same (IV, key) pair reuse problem. There is a Synthetic Initialization Vector (SIV) mode as nonce-misuse resistance ( paper, rfc8452 ) that eliminates this.

  • Long message distinguisher: The CTR mode is designed with a Pseudo-Random-Function (PRF). When using AES in CTR mode, we use it with Pseudo Random Permutation (PRP); $$E_k\colon {0,1}^n \to {0,1}^n.$$ Whit PRP as long as the message blocks are not repeated the sequence $E_k(0), E_k(1), \dots, E_k(\ell - 1)$ with $\ell < 2^n$ is not repeated. If the message with length $\ell$-block has no repeated block this is no problem. If we approach the message as uniform random block then we expect a collision $\ell \approx \sqrt{2^n} = 2^{n/2}$ by the birthday paradox/attack.

    When used with AES-128 for long messages check for the repeat. The repeat enables the attacker to distinguish this from uniform random with non-negligible probability.

    In short, a duplicate ciphertext leaks that the messages are different.

Other advantages:

  1. No need the decryption: Doesn't require decryption of the block cipher. This is very helpful in constraint environments. Simplifies the software and hardware code, too.

  2. No need PRP: Doesn't need a block cipher (PRP) at all. A hash function can be used like in the ChaCha series.

  3. Prepocessing: the keystream generated by the CTR mode can be prepared before. This can help to use buffers.

A little history of CTR

CTR mode was introduced by Whitfield Diffie and Martin Hellman in 1979

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Test Magic links:

[meta] – link to the current site's Meta; link text is the site name (e.g. "Meta Super User"). Does nothing if the site doesn't have (or already is) a Meta site.

[main] – like [meta], just the other way around.

[edit] – link to the edit page for the post the comment is on, i.e. /posts/{id}/edit. Link text is "edit" (capitalization is respected).

Help center links. Link text for all of these is "help center": [help] should be obvious. [meta-help] links to "What is meta?" (/help/whats-meta) [help/on-topic] links to "What topics can I ask about here?" (/help/on-topic) [help/dont-ask] links to "What types of questions should I avoid asking?" (/help/dont-ask) [help/behavior] links to "What kind of behavior is expected of users?" (/help/behavior).

[tour] and [meta-tour] – equivalent to the FAQ version, but links to the site's Tour page (resp. the meta site's Tour page). Link text is "tour" (capitalization is respected). Legacy names [about] and [meta-about] are still supported.

[ask] – link to the "How to Ask" page

[answer] – link to the "How to Answer" page.

Links to the front page of Stack Exchange sites (link text is the site name): [so] – link to Stack Overflow [su] – link to Super User [sf] – link to Server Fault [metase]/[meta.se] – link to Meta Stack Exchange [ubuntu.se] – link to Ask Ubuntu [mathoverflow.se] – link to MathOverflow [a51] – link to Area 51 [se] – link to the Stack Exchange Localized Stack Overflow sites can be linked as [es.so] – link to Stack Overflow en español [ja.so] – link to スタック・オーバーフロー [pt.so] – link to Stack Overflow em Português [ru.so] – link to Stack Overflow на русском All other Stack Exchange sites, except Stack Apps: [something.se] – link to something.stackexchange.com, if that site exists. Link text is the site name. [sitename.meta.se] or [meta.sitename.se] – link to a site-specific Meta site. Link text is "Meta ".

[chat] – link to the current site's chat site ne showing a list of active rooms from the referring site), the link text being "{site name} Chat".

On Stack Overflow and localized Stack Overflow sites: [mcve], [reprex], [repro], [mre] and [example] – link to the Minimal Complete & Verifiable Example page for the site.

Tags (these work in questions, answers, comments, and chat, but are not formatted as tags in comments): [Note that if you're on meta, will still point to the main site. Except on Meta Stack Exchange, which doesn't have a main, makes no difference from .] creates a link to the named tag on the main site. creates a link to a tag on meta. The text is linked

Supported magic links in chat

In chat, only a limited subset of the magic links listed for comments work, plus one chat-specific magic link.

Chat supports the following magic links: [meta], [main], [ask], [answer], all the links to specific sites, and tag links (with tag formatting). Chat also adds [chat-faq], which results in "chat faq".

The tag magic links work as expected on Stack Overflow Chat and Meta Stack Exchange Chat. However, on Stack Exchange Chat, the chat room in which you use the magic link must be associated with a specific Stack Exchange site, and will take on the formatting of tags on that site.

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| improve this answer | |


Well, now we know Zalgo works!



  <p>Wow. </p>

| improve this answer | |

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