Upgrade to Pro — share decks privately, control downloads, hide ads and more …

∞ things I didn’t know about HTML, CSS, and Jav...

Sponsored · Your Podcast. Everywhere. Effortlessly. Share. Educate. Inspire. Entertain. You do you. We'll handle the rest. →
Avatar for Mathias Bynens Mathias Bynens
March 01, 2014
Programming
11
3.9k

∞ things I didn’t know about HTML, CSS, and JavaScript @ Kod.io 2014

Slides for my talk on random web development fun facts at Kod.io 2014.

Avatar for Mathias Bynens

Mathias Bynens

March 01, 2014
Tweet

More Decks by Mathias Bynens

See All by Mathias Bynens
V8 internals for JavaScript developers @ Fronteers 2018
Avatar for Mathias Bynens mathiasbynens
3
520
V8 internals for JavaScript developers
Avatar for Mathias Bynens mathiasbynens
2
1k
What’s new in ES2018?
Avatar for Mathias Bynens mathiasbynens
2
160
V8 internals for JavaScript developers
Avatar for Mathias Bynens mathiasbynens
1
190
Preventing timing attacks on the web @ Fronteers Jam 2016
Avatar for Mathias Bynens mathiasbynens
4
280
Front-End Performance: The Dark Side @ ColdFront Conference 2016
Avatar for Mathias Bynens mathiasbynens
1
510
Hacking with Unicode in 2016
Avatar for Mathias Bynens mathiasbynens
15
15k
Front-End Performance: The Dark Side @ Fronteers Spring Conference 2016
Avatar for Mathias Bynens mathiasbynens
16
57k
3.14 things I didn’t know about CSS @ CSSConf.asia 2015
Avatar for Mathias Bynens mathiasbynens
4
1.2k

Other Decks in Programming

See All in Programming
CSC307 Lecture 10
Avatar for Javier Gonzalez-Sanchez javiergs
PRO
1
660
AIエージェントのキホンから学ぶ「エージェンティックコーディング」実践入門
Avatar for Masahiro Nishimi masahiro_nishimi
5
480
フロントエンド開発の勘所 -複数事業を経験して見えた判断軸の違い-
Avatar for Yoichiro Kubo heimusu
7
2.8k
Grafana：建立系統全知視角的捷徑
Avatar for Blueswen blueswen
0
330
副作用をどこに置くか問題：オブジェクト指向で整理する設計判断ツリー
Avatar for Koya Masuda koxya
1
610
登壇資料を作る時に意識していること #登壇資料_findy
Avatar for konifar konifar
4
1.4k
AWS re:Invent 2025参加 直前 Seattle-Tacoma Airport(SEA)におけるハードウェア紛失インシデントLT
Avatar for tetutetu214 tetutetu214
2
120
AIエージェント、”どう作るか”で差は出るか？ / AI Agents: Does the "How" Make a Difference?
Avatar for r-kagaya rkaga
4
2k
ノイジーネイバー問題を解決する 公平なキューイング
Avatar for Shoichi Ochi occhi
0
110
組織で育むオブザーバビリティ
Avatar for ryotaro kobayashi ryota_hnk
0
180
CSC307 Lecture 05
Avatar for Javier Gonzalez-Sanchez javiergs
PRO
0
500
Oxlint JS plugins
Avatar for kazupon kazupon
1
980

Featured

See All Featured
What’s in a name? Adding method to the madness
Avatar for The Alliance productmarketing
PRO
24
3.9k
Bridging the Design Gap: How Collaborative Modelling removes blockers to flow between stakeholders and teams @FastFlow conf
Avatar for Kenny Baas-Schwegler baasie
0
450
WCS-LA-2024
Avatar for Leonardo Collado-Torres lcolladotor
0
450
A Soul's Torment
Avatar for Nat Ma seathinner
5
2.3k
Efficient Content Optimization with Google Search Console & Apps Script
Avatar for Katarina Dahlin katarinadahlin
PRO
1
330
Primal Persuasion: How to Engage the Brain for Learning That Lasts
Avatar for Mike Taylor tmiket
0
250
Exploring anti-patterns in Rails
Avatar for Elle Meredith aemeredith
2
250
The Impact of AI in SEO - AI Overviews June 2024 Edition
Avatar for Aleyda Solis aleyda
5
730
What does AI have to do with Human Rights?
Avatar for Per Axbom axbom
PRO
0
2k
The Invisible Side of Design
Avatar for Vitaly Friedman smashingmag
302
51k
Principles of Awesome APIs and How to Build Them.
Avatar for Keavy McMinn keavy
128
17k
Visualizing Your Data: Incorporating Mongo into Loggly Infrastructure
Avatar for mongodb mongodb
49
9.9k

Transcript

  1. @mathias · #kodio_2014 Ten things I didn’t know about HTML

  2. @mathias

  3. Ten things I didn’t know about HTML @mathias · #kodio_2014

  4. ∞ things I didn’t know about HTML, CSS & JavaScript

    @mathias · #kodio_2014

  5. Back to the ’90s kickin’ it old skool

  6. None

  7. Background colors <body bgcolor="pink"></body>

  8. Background colors <body bgcolor="pink"></body>

  9. Background colors <body bgcolor="#ffc0cb"></body>

  10. Background colors <body bgcolor="ffc0cb"></body>

  11. Background colors <body bgcolor="#f3f"></body> " #FF33FF

  12. Background colors <body bgcolor="f3f"></body> " #0F030F

  13. Background colors <body bgcolor="sick"></body> " #00C000

  14. Background colors <body bgcolor="MrT"></body> " #000000

  15. Background colors <body bgcolor="chucknorris"></body> " #C00000

  16. Background colors <body bgcolor="crap"></body> " #C0A000

  17. Background colors <body bgcolor="!"></body> " #000000

  18. Background colors <body bgcolor="kodio"></body> " #00D000

  19. Background colors http://mths.be/bgcolor

  20. Background colors http://mths.be/bgcolor

  21. “Valid HTML” conformance criteria

  22. Document Type Definition

  23. DTD <head> <p>Lorem ipsum.</p> </head>

  24. DTD <kitchensink>

  25. DTD fail <input type="date" placeholder="foo">

  26. DTD fail <input type="date" placeholder="foo"> <table> <tr><td>foo</td></tr> <tr><td colspan="2">bar</td></tr> </table>

  27. DTD fail <input type="date" placeholder="foo"> → can still be checked

    by a computer <table> <tr><td>foo</td></tr> <tr><td colspan="2">bar</td></tr> </table>

  28. Computer says no <img src="foo.png" alt=""> <time datetime="2013-10-03">LOL</time> <blockquote>not a

    quote</blockquote>

  29. Computer says no <img src="foo.png" alt=""> → can only be

    checked by a human <time datetime="2013-10-03">LOL</time> <blockquote>not a quote</blockquote>

  30. Take-away Don’t obsess about HTML validation. • not the whole

    story • validators have bugs, too Functionality trumps validation anyway.
 <meta http-equiv="X-UA-Compatible" content="IE=edge">

  31. Character references aka. “entities”

  32. Character references <!-- valid and reliable: --> <p>foo &amp; bar</p>

    <!-- renders as “foo & bar” -->

  33. ;

  34. github:twbs/bootstrap#3057

  35. github:twbs/bootstrap#3057

  36. ;

  37. ; PRETENDS TO BE OPTIONAL BREAKS STUFF WHEN OMITTED

  38. Character references <!-- valid and reliable: --> <p>foo &amp; bar</p>

    <!-- renders as “foo & bar” -->

  39. Character references <!-- invalid, but reliable: --> <p>foo &amp bar</p>

    <!-- renders as “foo & bar” -->

  40. Character references <!-- invalid, and confusing: --> <p title="foo&ampbar"> foo&ampbar

    </p> <!-- title renders as “foo&ampbar” --> <!-- text renders as “foo&bar” -->

  41. Character references <!-- valid and reliable: --> <p>foo & bar</p>

    <!-- renders as “foo & bar” --> http://mths.be/bdu

  42. Character references <!-- valid and reliable: --> <p>foo &gt; bar</p>

    <!-- renders as “foo > bar” -->

  43. Character references <!-- invalid, but reliable: --> <p>foo &gt bar</p>

    <!-- renders as “foo > bar” -->

  44. Character references <!-- invalid, and confusing: --> <p title="foo&gtbar"> foo&gtbar

    </p> <!-- title renders as “foo&gtbar” --> <!-- text renders as “foo>bar” -->

  45. Character references <!-- valid and reliable: --> <p>foo > bar</p>

    <!-- renders as “foo > bar” -->

  46. Character references <p>foo&#x85;bar</p> <!-- which symbol is this? --> <!--

    how will it render? -->

  47. Character references <p>foo&#x85;bar</p> <!-- which symbol is this? --> <!--

    how will it render? -->

  48. &#x85; is U+0085, right?

  49. &#x85; is U+0085, right? ✘

  50. Nope, not in HTML!

  51. Nope, not in HTML!

  52. …but it is in XHTML

  53. Character references

  54. Tags

  55. Valid HTML <!DOCTYPE html>
 <html>
 <head>
 <title>Foo</title>
 </head>
 <body>
 …


    </body>
 </html>

  56. Valid HTML <!DOCTYPE html>
 <html>
 <head>
 <title>Foo</title>
 </head>
 <body>
 …


    </body>
 </html>

  57. Valid HTML <!DOCTYPE html>
 <html>
 <head>
 <title>Huh?</title>
 <body>
 …


  58. Valid HTML <!DOCTYPE html>
 <html>
 <head>
 <title>Huh?</title>
 <body>
 …


  59. Valid HTML <!DOCTYPE html>
 <title>lolwut</title>
 …


  60. None
  61. None

  62. ^ n FTFY

  63. Using CSS without HTML

  64. None
  65. None

  66. CSS without HTML $ curl -i http://mathiasbynens.be/demo/css-without-html HTTP/1.1 200 OK

    Date: Wed, 03 Oct 2013 13:33:37 GMT Link: <css-without-html.css>;rel=stylesheet Content-Length: 0 Content-Type: text/html; charset=UTF-8 http://mths.be/bpe

  67. CSS without HTML $ curl -i http://mathiasbynens.be/demo/css-without-html HTTP/1.1 200 OK

    Date: Wed, 03 Oct 2013 13:33:37 GMT Link: <css-without-html.css>;rel=stylesheet Content-Length: 0 Content-Type: text/html; charset=UTF-8 http://mths.be/bpe
  68. None

  69. Font family names

  70. CSS html {
 font-family: 'Comic Sans MS';
 } “If there’s

    whitespace in the font family name, it must be quoted.”

  71. CSS html {
 font-family: Comic Sans MS;
 } “If there’s

    whitespace in the font family name, it must be quoted.” http://mths.be/bft

  72. CSS html {
 font-family: 456bereastreet;
 }

  73. CSS html {
 font-family: 456bereastreet;
 }

  74. CSS html {
 font-family: \34 56bereastreet;
 }

  75. CSS html {
 font-family: \34 56bereastreet;
 }

  76. CSS html {
 font-family: '456bereastreet';
 }

  77. CSS http://mths.be/bjm

  78. Attribute values

  79. Attribute values <a href="foo">…</a> <style> a[href="foo"] { background: hotpink; }

    </style>

  80. Attribute values <a href=foo>…</a> <style> a[href=foo] { background: hotpink; }

    </style>

  81. Attribute values <a href=foo|bar>…</a> <style> a[href=foo|bar] { background: hotpink; }

    </style>

  82. Attribute values <a href=foo|bar>…</a> <style> a[href=foo|bar] { background: hotpink; }

    </style>

  83. Attribute values <a href=foo|bar>…</a> <style> a[href="foo|bar"] { background: hotpink; }

    </style> http://mths.be/bal

  84. Attribute values http://mths.be/bjn

  85. Handling user input

  86. http://mths.be/bqv

  87. http://mths.be/bqv

  88. Characters in JS

  89. JavaScript string length >> 'A'.length // U+0041 1 >> 'A'

    == '\u0041' true >> 'B'.length // U+0042 1 >> 'B' == '\u0042' true

  90. String length ≠ char count >> 'A'.length // U+1D400 2

    >> 'A' == '\uD835\uDC00' true >> 'B'.length // U+1D401 2 >> 'B' == '\uD835\uDC01' true http://mths.be/bed

  91. Surrogate pairs // for non-BMP code points (> 0xFFFF) function

    getSurrogates(codePoint) { var high = Math.floor((codePoint - 0x10000) / 0x400) + 0xD800; var low = (codePoint - 0x10000) % 0x400 + 0xDC00; return [ high, low ]; } ! function getCodePoint(high, low) { var codePoint = (high - 0xD800) * 0x400 + low - 0xDC00 + 0x10000; return codePoint; } ! >> getSurrogates('A'); // U+1D400 [ 0xD835, 0xDC00 ] >> getCodePoint(0xD835, 0xDC00); 0x1D400 http://mths.be/bed

  92. JS string character count function countSymbols(string) { return punycode.ucs2.decode(string).length; }

    ! >> countSymbols('A') // U+0041 1 >> countSymbols('A') // U+1D400 1 http://mths.be/punycode

  93. JS variable names

  94. Which is invalid? var H ̹̙̦̮͉̩̗̗ ͧ̇̏̊̾ Eͨ͆͒̆ͮ̃ ͏̷̮̣̫̤̣Cͯ̂͐ ͏̨̛͔̦̟͈̻O

    ̜͎͍͙͚̬̝̣ ̽ͮ͐͗̀ͤ̍̀ ͢ M̴̡̲̭͍͇̼̟̯̦ ̉̒͠ Ḛ̛̙̞̪̗ ͥ ͤͩ̾͑̔͐ ͅ Ṯ̴̷̷̗̼͍ ̿̿̓̽͐ H ̙̙ ̔̄ ͜ ; var "_ಠಠ_"; var ໦ϗ îਓƎ ℵೋീΔେ; var ʃː λ ˀπ ᐩᐨᐟᑉᐦᐸᐳ\u200C; var a; http://mths.be/ber

  95. ♥ JS var H ̹̙̦̮͉̩̗̗ ͧ̇̏̊̾ Eͨ͆͒̆ͮ̃ ͏̷̮̣̫̤̣Cͯ̂͐ ͏̨̛͔̦̟͈̻O ̜͎͍͙͚̬̝̣

    ̽ͮ͐͗̀ͤ̍̀ ͢ M̴̡̲̭͍͇̼̟̯̦ ̉̒͠ Ḛ̛̙̞̪̗ ͥ ͤͩ̾͑̔͐ ͅ Ṯ̴̷̷̗̼͍ ̿̿̓̽͐ H ̙̙ ̔̄ ͜ ; // valid var !_ಠಠ_!; // valid var ໦ϗ îਓƎ ℵೋീΔେ; // valid var ʃː λ ˀπ ᐩᐨᐟᑉᐦᐸᐳ\u200C; // valid var a; // syntax error http://mths.be/ber

  96. /^(?!(?:do|if|in|for|let|new|try|var|case|else| enum|eval|false|null|this|true|void|with|break| catch|class|const|super|throw|while|yield|delete| export|import|public|return|static|switch|typeof| default|extends|finally|package|private|continue| debugger|function|arguments|interface|protected| implements|instanceof)$)[$A-Z\_a-z\xaa\xb5\xba \xc0-\xd6\xd8-\xf6\xf8-\u02c1\u02c6-\u02d1\u02e0- \u02e4\u02ec\u02ee\u0370- \u0374\u0376\u0377\u037a-\u037d\u0386\u0388-

    \u038a\u038c\u038e-\u03a1\u03a3-\u03f5\u03f7- \u0481\u048a-\u0527\u0531-\u0556\u0559\u0561- \u0587\u05d0-\u05ea\u05f0-\u05f2\u0620-\u064a

  97. \u20f0\u2cef-\u2cf1\u2d7f\u2de0-\u2dff\u302a- \u302f\u3099\u309a\ua620-\ua629\ua66f\ua674- \ua67d\ua69f\ua6f0\ua6f1\ua802\ua806\ua80b\ua823- \ua827\ua880\ua881\ua8b4-\ua8c4\ua8d0- \ua8d9\ua8e0-\ua8f1\ua900-\ua909\ua926-\ua92d \ua947-\ua953\ua980-\ua983\ua9b3-\ua9c0\ua9d0- \ua9d9\uaa29-\uaa36\uaa43\uaa4c\uaa4d\uaa50- \uaa59\uaa7b\uaab0\uaab2-\uaab4\uaab7\uaab8\uaabe \uaabf\uaac1\uaaeb-\uaaef\uaaf5\uaaf6\uabe3- \uabea\uabec\uabed\uabf0-\uabf9\ufb1e\ufe00-

    \ufe0f\ufe20-\ufe26\ufe33\ufe34\ufe4d-\ufe4f \uff10-\uff19\uff3f]*$/

  98. JS variable names http://mths.be/bjo

  99. Questions? @mathias