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

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

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
490
V8 internals for JavaScript developers
Avatar for Mathias Bynens mathiasbynens
2
850
What’s new in ES2018?
Avatar for Mathias Bynens mathiasbynens
2
130
V8 internals for JavaScript developers
Avatar for Mathias Bynens mathiasbynens
1
160
Preventing timing attacks on the web @ Fronteers Jam 2016
Avatar for Mathias Bynens mathiasbynens
4
230
Front-End Performance: The Dark Side @ ColdFront Conference 2016
Avatar for Mathias Bynens mathiasbynens
1
390
Hacking with Unicode in 2016
Avatar for Mathias Bynens mathiasbynens
15
14k
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
1k

Other Decks in Programming

See All in Programming
Dissecting and Reconstructing Ruby Syntactic Structures
Avatar for ydah ydah
3
1.9k
KawaiiLT 登壇資料　キャリアとモチベーション
Avatar for 柊 hiiragi
0
160
fieldalignmentから見るGoの構造体
Avatar for kuro kuro_kurorrr
0
130
RubyKaigi Dev Meeting 2025
Avatar for Aaron Patterson tenderlove
1
1.3k
実践Webフロントパフォーマンスチューニング
Avatar for しーぴー cp20
45
9.9k
Bedrock×MCPで社内ブログ執筆文化を育てたい！
Avatar for Har1101 har1101
7
1.4k
Enterprise Web App. Development (1): Build Tool Training Ver. 5
Avatar for Koichi NAKAGAWA knakagawa
1
120
Memory API : Patterns, Performance et Cas d'Utilisation
Avatar for José josepaumard
1
160
generative-ai-use-cases(GenU)の推しポイント ～2025年4月版～
Avatar for Hideyuki Nagata hideg
1
370
状態と共に暮らす：ステートフルへの挑戦
Avatar for ypresto ypresto
3
1.1k
カオスに立ち向かう小規模チームの装備の選択〜フルスタックTSという装備の強み _ 弱み〜/Choosing equipment for a small team facing chaos ~ Strengths and weaknesses of full-stack TS~
Avatar for 株式会社ビットキー / Bitkey Inc. bitkey
1
130
Qiita Bash
Avatar for hiro mercury_dev0517
2
220

Featured

See All Featured
Fireside Chat
Avatar for paigeccino paigeccino
37
3.4k
Music & Morning Musume
Avatar for Bryan Veloso bryan
47
6.5k
How To Stay Up To Date on Web Technology
Avatar for Chris Coyier chriscoyier
790
250k
Visualization
Avatar for Eitan Lees eitanlees
146
16k
Save Time (by Creating Custom Rails Generators)
Avatar for Garrett Dimon garrettdimon
PRO
31
1.2k
RailsConf & Balkan Ruby 2019: The Past, Present, and Future of Rails at GitHub
Avatar for Eileen M. Uchitelle eileencodes
137
33k
[RailsConf 2023 Opening Keynote] The Magic of Rails
Avatar for Eileen M. Uchitelle eileencodes
29
9.4k
GitHub's CSS Performance
Avatar for Jon Rohan jonrohan
1030
460k
Building Flexible Design Systems
Avatar for Yesenia Perez-Cruz yeseniaperezcruz
329
39k
Code Reviewing Like a Champion
Avatar for maltzj maltzj
523
40k
Designing for humans not robots
Avatar for Tammie Lister tammielis
253
25k
Done Done
Avatar for chrislema chrislema
184
16k

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