🌞 (U+1F31E Sun With Face)
🌙 (U+1F319 Crescent Moon)

Testing out how headers work:

hello

hello

hello

hello

Trying to abuse KBD tags:

waffles

waffles

[tag:waffles]

[tag:waffles]

waffles

[waffles](https://meta.stackexchange.com/questions/tagged/unicorns)

Testing some stuff with flairs:

Render example for a Stacks editor bug report:

• One (this point is italic in the editor)
• Two
• Three

This is italic, and because of a lack of termination (#21), everything after is italic

Regular text

Formatting of images in tables:

These examples are made to see what methods work for getting the most out of a table's space.

Default behaviour:

The table adapts to the contents of the first cell, and the contents of the adjacent cell(s) are adapted to that of the first.
The second image in the second cell is forced below the first using a <br/> (or two, rather, so the images have a better looking gap between them):

Using the  

Using the HTML   entity to fill out the empty space due to the table cells adjusting to the width of the contents of the first cell:

Using   and <br/>

Using that same trick but preceded by a <br/> to force that the line of non-breaking spaces below the image (such a line can also be put above the image, logically), to prevent the scrollbar from appearing (thank you @Makyen!):

Using <img> entities with custom width set

Different aspect ratios behave differently, and there is still a lot of unused space in the table:

Using <img> entities with width and height

It takes a lot more work, but it's indeed doable (the burden of being a perfectionist, I presume). The numbers are guesswork, and the aspect ratios obviously don't correspond with the true dimensions of the images, but it looks good:

Width = 320, height = 640	Width = 370, height = 305 (of both images)

And here's how they all look when the viewport's width changes to something more narrow:

It seems the table with the images in <img> and only their width set wins the beauty contest when viewports of widths < 1265 px are taken into consideration, until the breaking point at 980 px occurs, and the right sidebar is removed. But then it immediately adapts to the viewport's width, so it only looks okay - depending on contents - for a few tens of pixels.

not quoted, but highlighted

printf("here's some code\n");
int x = 99 + 100;

quoted and highlighted

printf("here's some code\n");
int x = 99 + 100;

You should call foo(bar = TRUE). The bar argument is very important because it prevents foo overflow.

Stacks editor is broken. This is a proof.

Testing spoilers and code fences:

none ! code block ! Text block none ! code block ! Text block

Hmm...

none ! code block !
Text block
none ! code block !
Text block

none code block
Text block asd asd
Text block

The following text is from answer to: "How to indent a few lines in Markdown markup?" by AgainPsychoX. It is under a CC BY-SA 4.0 license.

This is normal text.

This gets indented, without enumeration nor dots.

Multiple levels seems to be possible?

Yes, but syntax gets messy, unless you write it single line :)

Testing something with new editor and its ability to convert local links to question titles.

Some links which should get converted to question titles:

• Quotes are ignored in search when there's a word/tag outside quotes
• DevOps.SE is in a favor of a mass-migration of questions based on topicality
• Minor alignment issue in Activity page Impact section's tooltip

Highlighting:

print('test')

Testing server-side rendering of NBSP in inline code:

" ".join(map(shlex.quote, sys.argv))

Text Fragment Linking

test1 [text](link)

test2 [text][ref]

test3: https://example.com/#:~:text=illustrative%20examples

test4: https://example.com/#:~:text=illustrative%20examples

test5 <a href="">...</a> works

<a href="https://example.com/#:%7E:text=illustrative%20examples">
<a href="https://example.com/#:%7E:text=illustrative%20examples">
<a href="https://example.com/#:%7E:text=illustrative%20examples">
<a href="https://example.com/#:%7E:text=illustrative%20examples">
<a href="https://example.com/#:~:text=illustrative%20examples">

Using all allowed URL Code points

https://url.spec.whatwg.org/#url-code-points

test1

test2

test3: https://example.com/!$'()*+./:;=?@_~&,-

test4: https://example.com/!$'()*+./:;=?@_~&,-

test5

<a href="https://example.com/#!$%27()*+./:;=?@_%7E&amp;,-">
<a href="https://example.com/#!$%27()*+./:;=?@_%7E&amp;,-">
<a href="https://example.com/#!$%27()*+./:;=?@_%7E&amp;,-">
<a href="https://example.com/#!$%27()*+./:;=?@_%7E&amp;,-">
<a href="https://example.com/#!$%27()*+./:;=?@_~&amp;,-">

• ~ : percent-encoded, unless <a> element used.
• ' : percent-encoded always

Tabs being converted to spaces

In code fences:

    this is a test
    this is a test
    this is a test

In a <pre><code> block:

 this is a test
    this is a test
    this is a test

In a <pre><code> block using HTML entities:

	this is a test
	this is a test
	this is a test

This is a test image:

HTML stuff (markup) in a Markdown table:

this is a test of embedding links into block quotes

Test wrong formatting from new editor:

Single line

`

const hello = "world";

`

Multi line

`

const hello = "world";

const foo = 42;

console.log(hello, foo);

`

Single line more backticks

`

const hello = "world";

`

Multi line more backticks

`

const hello = "world";

const foo = 42;

console.log(hello, foo);

`

Table | Foo | Bar | Baz | | --- | --- | --- | | 123 | 456 | 789 |

Fullwidth symbol and URL：https://example.com/

The rendering of the preview during editing and the actual rendering are different.

Posting an answer so that I can test stuff with comments

Editing so that other reviewers don't have to waste their time on a formatting sandbox answer (editing from the review queue marks the review item as completed).

This answer is to test some more complex link and image Markdown syntax.

The image used is:

• Icojam-Weathy-24-tornado.png https://i.sstatic.net/wRMuO.png
  original URL: http://www.iconarchive.com/show/weathy-icons-by-icojam/24-tornado-icon.html
  Artist: Icojam
  Iconset: Weathy Icons (25 icons)
  License: Public Domain

The original intent for this answer was to verify some more complex link and image Markdown to make sure that a couple of userscripts were parsing it correctly. However, in the process of creating these, I encountered a bug in at least the SE post preview parsing of the Markdown. I don't know until saving this if there are issues in the backend processing.

Bug identified (only SE post preview; works in post rendered in the backend: i.e. once it's saved):

No support for multi-line tooltips

Simple examples: working demo on CommonMark site

• This is a link with a multi-line tooltip using reference, [link text][ref], format
• This is a link with a multi-line tooltip using inline [link text](URL + title) format

More complex examples

multi-line text + image + multi-line text with multi-line tooltips (inner and outer) working demo on CommonMark site; not working in SE post edit preview

• This multi-line
  text is part
  of the link some more
  multi-line
  text

multi-line text + image + multi-line text with tooltips (inner and outer, both multi-line); working demo on CommonMark site; not working in SE post edit preview

• This multi-line
  text is part
  of the link Even
  this is
  some more link text

Links:

named/numbered: [link text][ref] format

"normal"

image with tooltips (inner and outer)

text + image with tooltips (inner and outer)

• This is part of the link

text + image + text with tooltips (inner and outer)

• This is part of the link some more text

multi-line text + image with tooltips (inner and outer)

• This multi-line
  text is part
  of the link

multi-line text + image + text with tooltips (inner and outer)

• This multi-line
  text is part
  of the link some more text

multi-line text + image + multi-line text with tooltips (inner and outer)

• This multi-line
  text is part
  of the link some more
  multi-line
  text

multi-line text + image + multi-line text with multi-line tooltips (inner and outer) working demo on CommonMark site; not working in SE post edit preview

• This multi-line
  text is part
  of the link some more
  multi-line
  text

[link text](URL + optional title/tooltip) syntax

"normal", no tooltip

link with tooltip

• just some link text

image with tooltip (inner and outer)

text + image with tooltip (inner and outer)

• This is part of the link

text + image + text with tooltip (inner and outer)

• This is part of the link this is some more text

multi-line text + image + text with tooltips (inner and outer)

• This multi-line
  text is part
  of the link Even this is some more link text

multi-line text + image + multi-line text with tooltips (inner and outer)

• This multi-line
  text is part
  of the link Even
  this is
  some more link text

multi-line text + image + multi-line text with tooltips (inner and outer, both multi-line); working demo on CommonMark site; not working in SE post edit preview

• This multi-line
  text is part
  of the link Even
  this is
  some more link text

More variations: different delimiters

link with tooltip (escaping the delimiter; should work in posts)

• title using " as delimiter
• title using ' as delimiter
• title using () as delimiter

SE Chat: More variations, different delimiters

SE Chat doesn't require escaping the delimiter on a tooltip interior to the tooltip and will display the escape. It also doesn't support a delimiter other than ".

link with tooltip (NOT escaping the delimiter; should not work in posts) See these in chat starting here

The following do not, and should not, work in SE posts. They are specific to SE Chat, which uses a different Markdown parser with somewhat different and more limited syntax.

• [title using " as delimiter](https://example.com/foo "tooltip: "tooltip: this is a title/tooltip [], with something in [brackets], (parenthesis), 'single quotes', and "double quotes" which don't use escaping; and all escaped [brackets], (parenthesis), 'single quotes', and "double quotes". Delimiter at the "end""): Works in SE chat, but the escaping for the single and double quotes is displayed in the title. The escaping of the parentheses and brackets are not displayed.
• [title using " as delimiter; not escaping delimiters](https://example.com/foo "tooltip: "tooltip: this is a title/tooltip [], with something in [brackets], (parenthesis), 'single quotes', and "double quotes" which don't use escaping; Delimiter at the "end""): Works in SE chat, with correct display in the title/tooltip, due to not escaping any delimiters.

Examples from CommonMark spec

Multi-line title: Example #196 from CommonMark spec (live CommonMark demo) NOT working in post edit preview:

foo

This is strikethrough font: abc

This is strikethrough font: <s>abc</s>

<kbd><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br>
</kbd>

So this is just a test of snippets. I see how it works: when you enter code, then click Results, nothing happens. You have to submit it, then it will work, then, finally, you can post your answer. Three steps instead of two. Okay. I just wish I could post all the nice little snippets I've accumulated over the years for my own use. Can't do that, because SO has lots of rules and it is easy to get banned. I know; I have. I'm very careful when I post questions, not to post them in the form of "here is a neat way to do something".

alert('hi');

.a {color:green;}

<div class=a>Test</div>

A new list?

1. This.
2. That.

Edits. Grace period edits?

Wait, what!?! I don’t own The Nineteenth Byte!

Raw links are linkified differently in live preview and rendered result?

Code https://github.com/
Code：https://github.com/
Code: https://github.com/
Code - https://github.com/
Code!https://github.com/
Code.https://github.com/
Code https://github.com/
Codehttps://github.com/

In live preview, the links are linkified if immediately prefaced by a punctuation. If the rendered result, a space is required.

Comment on this question: Why has the parsing of the &nbsp; in tables changed?

Adding &nbsp; isn't useful, just use correct markdown, you are missing a "|".

Your example:

So that instead of this:	I get this:
	Looks much better, right?

My example (use image and specify width):

1. I get this:

My example (no non-breaking spaces):

2. I get this:

My example (with a small number of non-breaking spaces):

3. I get this:

Adding the non-breaking spaces changes the size of the right column.

Notes:

Allowed attributes for <img>

The following attributes are allowed on the tag, in the order shown below. Note that the mobile theme enforces a maximum width of 90%, so specifying a height might not scale the image proportionally on the mobile sites.

Attributes must be specified in this order. You may omit attributes you do not want to specify, but specifying a later attribute before an earlier one will strip the tag.

1. src=""
2. width="" (1–999; plain number without any extensions like px)
3. height="" (1–999; plain number without any extensions like px; pay attention to order warning above)
4. alt=""
5. title=""

You would be better off using percentages to enforce a specific ratio of the images while using three separate images, but using a single image of a grid is probably the best solution.

I’m testing hyphens ("HYPHEN MINUS") on iOS 12. Specifically, typing multiple hyphens into the edit box. Typing 2 hyphens together results in a single "EM DASH".

Related question on the Ask Different Stack:
How do I type a hyphen in iOS 12?

The text in parentheses describes the resulting string after typing N hyphens.

Below this line is a single “hyphen” (HYPHEN)

-

Below this are 2 hyphens (EM DASH)

—

—

And 3 hyphens (EM DASH + HYPHEN)

—-

—

Four hyphens (EM DASH + EM DASH)

——

-—

Five hyphens (EM DASH + EM DASH + HYPHEN)

——-

Long press and second character (EN DASH)

–

Long press and third character (EM DASH)

—

Copy/paste

Hello -

• (BULLET - Long press and first character)

Saying "hyphen hyphen hyphen hyphen" results in 4 contiguous hyphens

Saying "dash" results in an "EN DASH" and "dash dash dash dash" results in 4 x "EN DASH + SPACE" (not contiguous).

– – – –