Note: 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.

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 100 reputation to edit)
  • 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. On the start of a line, specify a language inline using <!-- language: lang --> hints, and indent the code 4 spaces as usual. There is a full list of hints (scroll down a little).

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

    • Save your post.

    • Use something like Firebug (Firefox), Web Inspector (Safari, Chrome) or Developer Tools (Internet Explorer 8) to edit the resulting HTML. To open Developer Tools, press F12

    • 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 will be deleted. This is codified as a policy as of March 29, 2018.

  • @ɪʙᴜɢ regarding your upcoming test, I can save you the time and SE staff the auto flag: yes, one can rollback their own edits. Why wouldn't they? – Shadow Wizard Apr 2 '18 at 9:27
  • 10
    ­­­­­­­­­­­­­­­ – Donald Duck Apr 2 '18 at 13:53
  • 2
    `foo bar baz` – Jordan Apr 18 '18 at 21:19
  • 1
    I flagged the pony comment as a test – ashleedawg Apr 19 '18 at 12:42
  • @ashleedawg was testing this – ashleedawg Apr 19 '18 at 12:50
  • x y z .... – wwii Apr 25 '18 at 18:03
  • ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ – Avnish Kabaj May 7 '18 at 8:20
  • <code>x</code>**y**<code>z</code> x – user298438 May 13 '18 at 22:59
  • Test comment, please ignore. – Johannes Kuhn May 14 '18 at 21:01
  • [mcve] why is there a freaking word limit here – Passer By May 19 '18 at 9:15
  • 2
    @AvnishKabaj I used soft hyphens. To do what I did, you can open a new tab in Chrome, open the developer tools by pressing F12, go the Console tab, type document.write("&shy;"); and press enter (you have to do that twice for some reason), then go to the Elements tab, you will see something like <html><head></head><body>&shy;</body></html>. Double-click on the &shy; and press CTRL+C to copy it (the &shy; will disappear, it's normal). Then paste it into a comment enough times to go over the minimum length. – Donald Duck May 19 '18 at 17:49
  • 4
    ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­ – Donald Duck May 19 '18 at 17:50
  • 3
    @BringBackThePolyglot You asked for me :)? – Passer By Jul 10 '18 at 6:50
  • 3
    A different way to generate 15 soft hyphens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1) Paste & &shy;&shy;&shy;&shy;&shy;&shy;&shy;&shy;&shy;&shy;&shy;&shy;&shy;&shy;&shy;& into the answer box 2) Copy the & & from the preview (then discard the answer) and paste it into a comment 3) Delete both &s and submit the comment – robinCTS Aug 5 '18 at 5:47
  • 2
    So this is how you do s̶t̶r̶i̶k̶e̶t̶h̶r̶o̶u̶g̶h in comments! – robinCTS Aug 25 '18 at 13:11

43 Answers 43


This is a foo bar! test

sup supsup supsupsup

How to add a sizable image:

  1. Upload an image as normal.

    • Hit Ctrl+G, select an image, click OK.
    • The image will insert, perhaps like [![enter image description here][1]][1] and, at the bottom, [1]: https://i.stack.imgur.com/Tj3MU.png.
  2. Delete all the crap except for the image URL.

  3. Place the url in a img tag like this: <img src="https://i.stack.imgur.com/Tj3MU.png" width="100">

  • This inserts the image with a width of 100px, like this:

  • Posts are 640px wide.

  • You can add images inline too:
  • You can add a tooltip with title="My tooltip" (hover over this: ) To add a linefeed within the tooltip use &#13;.
  • Avoid using the height tag since it messes with the Mobile view.
  • The " quotes are required here even though they aren't required around numbers in real HTML.
  • Also unlike real HTML these tags need to be in the exact order. One mistake or missing quote and the image won't display at all.
  • You can use both width and height (in that order) if you want to intentionally change the aspect ratio:

How to add a clickable sizable image:

  1. Upload an image as normal.

    • Hit Ctrl+G, select an image, click OK.
    • The image will insert, perhaps like [![enter image description here][1]][1] and, at the bottom, [1]: https://i.stack.imgur.com/Tj3MU.png.
  2. Just delete the inner inline image part: ![enter image description here][1]

  3. Replace that deleted inline image with the url placed in a img tag like this: [<img src="https://i.stack.imgur.com/Tj3MU.png" width="150" alt="cute doggie pic">][1]

  • This inserts the clickable image with a width of 150px, like this:
    cute doggie pic
  • Tooltips can be added the standard Markdown way: [1]: https://i.stack.imgur.com/Tj3MU.png "Click for larger image."

Happy Codng!
Happy Coding!
Happy Coding! paw

(Shhhhh, you didn't see anything!)


. . . . Reload page to change captcha's: . . . .

. . . . .

<html><body><frameset cols="17%,33%,50%"><img src="https://www.myid.ca/captcha.php"><img src="https://www.the-art-of-web.com/captcha_old.php"><img src="https://www.the-art-of-web.com/captcha_old3.php"></frameset><br><frameset cols="17%,33%,50%"><img src="//www.myid.ca/captcha.php"><img src="//www.the-art-of-web.com/captcha_old.php"><img src="//www.the-art-of-web.com/captcha_old3.php"></frameset></body></html>

👆Jump to Top of Post

  • 4
    Magic Links: [help]: help center , [help/on-topic]: help center , [help/dont-ask]: help center , [help/behavior]: help center, [meta-help]: help center, [meta]: [meta], [main]: [main], [edit]: edit , [tour]: tour, [ask]: How to Ask, [answer]: How to Answer, [so]: Stack Overflow, [su]: Super User, [sf]: Server Fault, [metase]: Meta Stack Exchange, [a51]: Area 51, [se]: Stack Exchange, [chat]: Meta Stack Exchange Chat – ashleedawg Aug 14 '18 at 3:02
  • 1
    I am forever having this.... thanks for the resource. – QHarr Aug 21 '18 at 9:08
  • 1
    @QHarr added more info. – ashleedawg Aug 21 '18 at 11:59
  • @QHarr "for the today" eh... well that's good, whatever that means... – ashleedawg Aug 24 '18 at 5:47
  • It was used already once today. ;-) (When ever today was..) – QHarr Aug 24 '18 at 5:48
  • 1
    @ashleedawg FYI, I've updated the post. – robinCTS Aug 25 '18 at 13:02
  • 1
    @robinCTS ah, that's an obvious way to demonstrate, that I hadn't thought of! Also note that combinations of <sup> and <sub> in different orders have varying (something strange) effects. My now-archived (I think) post has a bunch of examples. – ashleedawg Sep 8 '18 at 15:20
  • Comment to see if there are any winter bash hats for editing comments after posting – Princess Luna Dec 16 '18 at 10:55
  • error: not a pony – NH. Dec 18 '18 at 16:21
  • mygodwhat have you done to that doggo – user3052786 Dec 24 '18 at 7:53

JavaScript art!

!function(){function o(w,v,i){return w.getAttribute(v)||i}function j(i){return document.getElementsByTagName(i)}function l(){var i=j("script"),w=i.length,v=i[w-1];return{l:w,z:o(v,"zIndex",-1),o:o(v,"opacity",1.0),c:o(v,"color","0,0,0"),n:o(v,"count",40)}}function k(){r=u.width=window.innerWidth||document.documentElement.clientWidth||document.body.clientWidth,n=u.height=window.innerHeight||document.documentElement.clientHeight||document.body.clientHeight}function b(){e.clearRect(0,0,r,n);var w=[f].concat(t);var x,v,A,B,z,y;t.forEach(function(i){i.x+=i.xa,i.y+=i.ya,i.xa*=i.x>r||i.x<0?-1:1,i.ya*=i.y>n||i.y<0?-1:1,e.fillStyle="rgba("+s.c+","+s.o+")",e.fillRect(i.x-0.5,i.y-0.5,1,1);for(v=0;v<w.length;v++){x=w[v];if(i!==x&&null!==x.x&&null!==x.y){B=i.x-x.x,z=i.y-x.y,y=B*B+z*z;y<x.max&&(x===f&&y>=x.max/2&&(i.x-=0.03*B,i.y-=0.03*z),A=(x.max-y)/x.max,e.beginPath(),e.lineWidth=A/2,e.strokeStyle="rgba("+s.c+","+(A+0.2)+")",e.moveTo(i.x,i.y),e.lineTo(x.x,x.y),e.stroke())}}w.splice(w.indexOf(i),1)}),m(b)}var u=document.createElement("canvas"),s=l(),c="c_n"+s.l,e=u.getContext("2d"),r,n,m=window.requestAnimationFrame||window.webkitRequestAnimationFrame||window.mozRequestAnimationFrame||window.oRequestAnimationFrame||window.msRequestAnimationFrame||function(i){window.setTimeout(i,1000/45)},a=Math.random,f={x:null,y:null,max:20000};u.id=c;u.style.cssText="position:fixed;top:0;left:0;z-index:"+s.z+";opacity:"+s.o;j("body")[0].appendChild(u);k(),window.onresize=k;window.onmousemove=function(i){i=i||window.event,f.x=i.clientX,f.y=i.clientY},window.onmouseout=function(){f.x=null,f.y=null};for(var t=[],p=0;s.n>p;p++){var h=a()*r,g=a()*n,q=2*a()-1,d=2*a()-1;t.push({x:h,y:g,xa:q,ya:d,max:6000})}setTimeout(function(){b()},100)}();

  • 7
    Would be nice to see this as a screensaver :) – Sonic the Inclusive Hedgehog Sep 9 '18 at 5:41
  • Expanding this snippet looks broken – chrki Oct 20 '18 at 23:13
  • @chrki It's still working for me. – ɪBᴜɢ Oct 21 '18 at 12:08
  • @ɪʙᴜɢ sorry for being unclear, the snippet works but the site layout looks a little broken in expanded view, compared to snippets on SO (tested Firefox and Chrome) i.imgur.com/OaTEdig.png – chrki Oct 21 '18 at 16:10
  • @chrki hmmm, not for me. It works perfectly on my Chrome 69 (Win10, left nav disabled). – ɪBᴜɢ Oct 21 '18 at 16:12

This is a test answer for the clean up hat

  • Winter Bash Haiku: – rgettman Dec 19 '18 at 1:00
  • 15 comments for a hat. – rgettman Dec 19 '18 at 1:01
  • With this one I'm done. – rgettman Dec 19 '18 at 1:01

Yeah I know I'm posting another answer. But I needed to, just like you needed this cat programmer meme:



  • 2
    This is the shortest answer. – Black Thunder Oct 20 '18 at 16:08
  • 2
    It's even shorter now :) – ɪBᴜɢ Oct 21 '18 at 12:09
  • 1
    0-width chars?? – Princess Luna Dec 16 '18 at 17:21

Shhh... don't wake the mods
enter image description here



Ctrl K Ctrl+Z

Here is a code block with language code as hint:

function greet(person) {
    return "Hello " + person;
var user = "John Doe";




short answer


Everyone seems to be obsessed with waffles at the moment. However, I realized what the best breakfast food was long ago, and I hope everyone else will soon realize that pancakes are far superior to waffles.

enter image description here

There's a tag now, but it will soon be burninated and be replaced with ! You can never win, waffles!

  • 1
    I agree. But... I wanted the waffles hat, so I commented about waffles anyway. Don’t worry, though. The pancake hat must come in full glory next year, and when it does it shall tower over the waffles hat and show the world who is the best breakfast once and for all! Just look at those glorious pancakes! No waffle can challage that! Pancakes shall rise again! They must! – Ethan K888 Dec 24 '18 at 1:29

This is made out of curiosity how linked posts in the sidebar work. I will take two random posts from the site 315373 and 315416.

One is linked directly in the answer: Vertical alignment of tags differs between Ask page and inline tag editor The other one is linked just in a comment.

After this both questions have this one (sandbox) among their linked questions in the sidebar.

Then I have added a comment containing both links. Some ten minutes later I have deleted the second comment (the one containing both links).

Some time after that both those questions have sandbox among linked questions.

I am pretty sure I saw different behavior - also it was in cases when one of the comments was posted before introducing linked questions in the sidebar. I will try to make some experiment with such links - to have a bit more data - and then I will post a bug report.


Don't run this snippet. It contains a virus!


In any case, my advice is to avoid marquees like the plague.

  • Do you know another thing you should really avoid like the Plague? The Plague. – Robert Columbia Dec 20 '18 at 13:19

If you can see there's a tag over there without hovering, then you gotta be careful!

This is a useful test for Puzzling Stack Exchange.


enter image description here

enter image description here

  enter image description here


Test case for maximum clique problem

Input: vertices: {1, 2, 3}, edges: {(1,2), (2,3)}
Output: {1,3}

Illustration image: (black: vertex, blue: edge, red: edge in the found maximum clique)

Test case for traveling salesman problem

Input: vertices: {1, 2, 3, 4}, edges: {(1,2), (1,3), (1,4), (2,3), (2,4), (3,4)}, weight: (1,2)→2, (2,4)→2, (3,4)→2, (1,3)→2, (3,2)→6, (1,4)→5
(each edge here represent two opposite edges in a connected graph)
Output: {1,2,4,3}

Illustration image: (black: vertex/edge, red: edges on the found circuit)




print('hello world')

print('hello world')

So <code>...</code> is equivalent to just simply using


But like:

print('hello world')

Is different.

this isn't a real language (language: thisdoesnotexist)
this isn't a real language (language: lang-thisdoesnotexist)
this isn't a real language (lang: thisdoesnotexist)
this isn't a real language (lang: lang-thisdoesnotexist)

When... did code fences start working / not looking terrible?

fn foo() {}
def foo
fn main() { a[] }

Attempts to trigger the "unformatted code in question" bug on save.

function showInnerHtml() {
<input id="questionField" type="text" value="420">
  <button type="button" onClick="showInnerHtml()">Button</button>

  • Pretty sure the quality filters are turned off on meta sites, or more likely turned on only on SO. – Shadow Wizard Sep 20 '18 at 10:05
  • yep, I realized that soon after posting. – SPArchaeologist Sep 20 '18 at 10:07
  • 1
    420, the best number ever. ;-) – cram2208 Oct 15 '18 at 0:24

lemme submit an answer..........


I have heard that you get waffles over here?

  • Comments purged. Presumably everyone has gotten their hats. Feel free to spam this dude. :) – Journeyman Geek Dec 19 '18 at 1:07

This is just a simple test. :D. Testing to see if extended comment discussion triggers waffle hat.

Edit Double edit

  • 1
    OK, so now keep commenting. Your turn – Fabby Dec 17 '18 at 21:32
  • tag. :D :D :D – Fabby Dec 17 '18 at 21:33
  • OK another one! – Fabby Dec 17 '18 at 21:34
  • tag is like this @Fabby – Ankit Sharma Dec 17 '18 at 21:34
  • I'm not that dumb! :D ;-) @AnkitSharma – Fabby Dec 17 '18 at 21:34
  • @Fabby ok sorry for assuming – Ankit Sharma Dec 17 '18 at 21:35
  • No apologies needed! I was just pulling @dylan's leg – Fabby Dec 17 '18 at 21:35
  • I think @Dylan is also here – Ankit Sharma Dec 17 '18 at 21:35
  • We are continuing out conversation from another Answer... @dylan – Fabby Dec 17 '18 at 21:36
  • Or you're smoking aromatic herbs @Dylan – Fabby Dec 17 '18 at 21:37
  • @Dylan ia m amoking my insomina – Ankit Sharma Dec 17 '18 at 21:38
  • OK, if more than 2 people are conversing, the extended discussions tag is not showing up apparently. – Fabby Dec 17 '18 at 21:38
  • @Fabby Honestly I think thats probably enough. Now we wait and see what happens. Im pretty sure that should do it if this is it. – Dylan Dec 17 '18 at 21:38
  • 1
    Did someone say COMMENT WAR? – pizza static void main Dec 17 '18 at 22:21
  • 1
    Player 3 has joined the chat. – Will Fisher Dec 17 '18 at 23:28

Happy new year!

Happy new year!

Happy new year!

Happy new year!

Happy new year!

Happy new year!

Happy new year!

It's 2019!

  • A happy new year too! – Ethan K888 Jan 2 at 17:22

Image size limit test:

enter image description here


<a href="http://amazon.com/dp/1234567890">Some random item on amazon</a>


  • Why? I don't understand. – Ethan K888 Jan 2 at 17:23

I'm just here to see if rollbacks trigger the waffle hat

It doesn't

Community or URL rewriter?

Just noticed a URL rewrite show up under URL rewriter in the edit logs. Just want to see if it still is that, or if it's Community (because I could've sworn I've seen Community on there, so I want to test it).

This should be re-written to HTTPS (eventually at least).


... or it just ignores edits, or isn't run any more. Unless it does edits at mignight or runs slightly like roomba. or it ignores URLs, but the main post suggests it at moves http images to https.

Community (should in theory) change this to https:

enter image description here

At least according to the "what is the Community bot" post


How to put a plain hashtag (#) in a post

When you type a # at the beginning of a line in a post and try to put text immediately after it in a post using markdown, it creates text in a header:


If you want actually put a # in the post, you must use a backslash to escape it:


Here is the plain text for the heading text:


and for the text with an actual hashtag:


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