People don't give a f**k of JavaScript - Dutch Mobile Conference 2014

People don't give a f**k of JavaScript - Dutch Mobile Conference 2014

People don't give a f**k of JavaScript. You shouldn't either. We are here to do stuffs, whether you call them websites, web applications, web services or hybrid apps. People want to perform tasks, not listen you talking about your favourite programming language. So, use the one you feel more comfortable with and just release the next big thing. But, if your favourite language is JavaScript, let's write better code. What does better means? Better for developers, better for devices, better for users.

In this talk, I'll describe some of the latest HTML5 APIs, many of which still experimental, that can help you develop great code. In a bunch of minutes, you'll see how to use:

- The High Resolution Time and the User Timing APIs to help yourself testing your code performances
- The Page Visibility and the Battery APIs to take care of devices' resources
- The Vibration and the GetUserMedia APIs to create better User Experiences

8b01a8b4d7a0a9079a4e97b1ddedbe56?s=128

Aurelio De Rosa

June 27, 2014
Tweet

Transcript

  1. PEOPLE DON'T GIVE A F**K OF JAVASCRIPT Aurelio De Rosa

    Amsterdam, Netherlands - 27 June 2014
  2. ABOUT ME (THE MOST BORING PART OF THE TALK!)

  3. WEB & APP DEVELOPER Previously employed at the University of

    Salerno, I'm now self-employed.
  4. THE LANGUAGES I USE

  5. WRITE ARTICLES FOR

  6. AUTHORED BOOKS JQUERY IN ACTION (3RD EDITION) INSTANT JQUERY SELECTORS

    (Shameless self-promotion!)
  7. None
  8. WHO ARE YOUR USERS?

  9. None
  10. None
  11. None
  12. None
  13. 3 QUESTIONS FOR YOU 1. Do you think they understand

    programming languages? 2. Do you think they know what's JavaScript? 3. Do you think they care about JavaScript?
  14. ...BUT I'M A DEVELOPER!

  15. None
  16. TASK

  17. EXPERIENCE

  18. “I'm a Java developer and I don't think I would

    trust a PHP developer enough to teach me something about the web” — Anonymous
  19. “There are only two kinds of languages: the ones people

    complain about and the ones nobody uses” — Bjarne Stroustrup
  20. “Pick one that feels right to you, and start building

    things. That's all that matters.” — Jeffrey Way
  21. None
  22. LET'S WRITE BETTER JAVASCRIPT

  23. PATTERN OF THE NEXT PART What Use Cases Methods, Properties

    and Events Example Browsers' Support (Desktop and Mobile) Use it today (Polyfills) Demo (live)
  24. ...Better for Developers

  25. PERFORMANCE MATTERS!

  26. Reference: http://torbit.com/blog/2012/09/19/some-interesting-performance-statistics/

  27. Reference: http://torbit.com/blog/2012/09/19/some-interesting-performance-statistics/

  28. LESSON: TEST AND IMPROVE YOUR WEBSITE'S PERFORMANCE

  29. HOW WE USE TO TEST PERFORMANCE

  30. DON'T BELIEVE ME? LOOK AT THIS SNIPPET v a r

    s t a r t T i m e = D a t e . n o w ( ) ; / / A t i m e c o n s u m i n g f u n c t i o n f o o ( ) ; v a r t e s t 1 = D a t e . n o w ( ) ; / / A n o t h e r t i m e c o n s u m i n g f u n c t i o n b a r ( ) ; v a r t e s t 2 = D a t e . n o w ( ) ; / / P r i n t r e s u l t s c o n s o l e . d e b u g ( " T e s t 1 t i m e : " + ( t e s t 1 - s t a r t T i m e ) ) ; c o n s o l e . d e b u g ( " T e s t 2 t i m e : " + ( t e s t 2 - t e s t 1 ) ) ;
  31. WHAT'S WRONG WITH DATE.NOW()? 1. It is not monotonically increasing

    2. Milliseconds precision 3. Precision of this timestamp varies between user agents 4. Different scope
  32. OK, I GOT IT. NOW WHAT?

  33. HIGH RESOLUTION TIME API

  34. WHAT IT DOES? Allows to accurately retrieve the number of

    milliseconds from the n a v i g a t i o n S t a r t attribute (belongs to the ). Navigation Timing API
  35. USE CASES Work with animation at high FPS rate Ensure

    a perfect audio-video synchronization
  36. METHODS The only method exposed is n o w (

    ) .
  37. EXAMPLE v a r s t a r t T

    i m e = p e r f o r m a n c e . n o w ( ) ; / / A t i m e c o n s u m i n g f u n c t i o n f o o ( ) ; v a r t e s t 1 = p e r f o r m a n c e . n o w ( ) ; / / A n o t h e r t i m e c o n s u m i n g f u n c t i o n b a r ( ) ; v a r t e s t 2 = p e r f o r m a n c e . n o w ( ) ; / / P r i n t r e s u l t s c o n s o l e . d e b u g ( " T e s t 1 t i m e : " + ( t e s t 1 - s t a r t T i m e ) ) ; c o n s o l e . d e b u g ( " T e s t 2 t i m e : " + ( t e s t 2 - t e s t 1 ) ) ;
  38. BROWSERS' SUPPORT

  39. DESKTOP BROWSERS' SUPPORT Explorer Chrome* Safari Firefox Opera 10+ 20+

    (-webkit) 24+ None 15+ 15+ Data updated to 21st June 2014 * As for now, p e r f o r m a n c e . n o w ( ) in Chrome on Windows returns a time almost always near the very start or the very end of a second ( ). issue #158234
  40. MOBILE BROWSERS' SUPPORT Explorer Android Chrome Safari Firefox Opera* 10+

    4.4+ 24+ None 15+ None Data updated to 21st June 2014 * Opera in the Mobile Browsers' support tables stand for Opera Mini
  41. HOW TO USE IT NOW w i n d o

    w . p e r f o r m a n c e = w i n d o w . p e r f o r m a n c e | | { } ; p e r f o r m a n c e . n o w = p e r f o r m a n c e . n o w | | f u n c t i o n ( ) { r e t u r n D a t e . n o w ( ) ; } ;
  42. TOO MANY VARS!

  43. USER TIMING API

  44. WHAT IT DOES? Allows to accurately measure and store performance

    of a JavaScript code
  45. USE CASES Performance testing

  46. METHODS m a r k ( ) c l e

    a r M a r k s ( ) m e a s u r e ( ) c l e a r M e a s u r e s ( ) g e t E n t r i e s B y T y p e ( ) g e t E n t r i e s B y N a m e ( )
  47. PROPERTIES n a m e e n t r y

    T y p e s t a r t T i m e d u r a t i o n
  48. EXAMPLE p e r f o r m a n

    c e . m a r k ( ' s t a r t T i m e 1 ' ) ; f o o ( ) ; p e r f o r m a n c e . m a r k ( ' e n d T i m e 1 ' ) p e r f o r m a n c e . m a r k ( ' s t a r t T i m e 2 ' ) ; b a r ( ) ; p e r f o r m a n c e . m a r k ( ' e n d T i m e 2 ' ) ; p e r f o r m a n c e . m e a s u r e ( ' d u r a t i o n T i m e 1 ' , ' s t a r t T i m e 1 ' , ' e n d T i m e 1 ' ) ; p e r f o r m a n c e . m e a s u r e ( ' d u r a t i o n T i m e 2 ' , ' s t a r t T i m e 2 ' , ' e n d T i m e 2 ' ) ; p e r f M e a s u r e s = p e r f o r m a n c e . g e t E n t r i e s B y T y p e ( ' m e a s u r e ' ) ; f o r ( v a r i = 0 ; i < p e r f M e a s u r e s . l e n g t h ; i + + ) { c o n s o l e . l o g ( ' N a m e : ' + p e r f M e a s u r e s [ i ] . n a m e + ' - ' + ' D u r a t i o n : ' + p e r f M e a s u r e s [ i ] . d u r a t i o n + ' \ n ' ) ; }
  49. BROWSERS' SUPPORT

  50. DESKTOP BROWSERS' SUPPORT Explorer Chrome Safari Firefox Opera 10+ 25+

    None None 15+ Data updated to 21st June 2014
  51. MOBILE BROWSERS' SUPPORT Explorer Android Chrome Safari Firefox Opera 10+

    4.4+ 25+ None None None Data updated to 21st June 2014
  52. HOW TO USE IT NOW usertiming.js

  53. ...Better for Devices

  54. PAGE VISIBILITY API

  55. WHAT IT DOES? Provides information about the page visibility's status

    Fires events about changes of the page visibility's status
  56. USE CASES Stop sending requests to the server for updates

    Pause a video or a song Stop the time counter of an intermediate ads page
  57. PROPERTIES h i d d e n v i s

    i b i l i t y S t a t e (h i d d e n , v i s i b l e , p r e r e n d e r , u n l o a d e d )
  58. EVENTS The only event exposed is v i s i

    b i l i t y c h a n g e .
  59. EXAMPLE v a r v i e w s =

    0 ; v a r c o u n t V i e w s = f u n c t i o n ( ) { i f ( d o c u m e n t . h i d d e n = = = f a l s e ) { v i e w s + + ; c o n s o l e . l o g ( " V i s i t " + v i e w s ) ; } } ; / / R u n t h e f u n c t i o n t h e f i r s t t i m e c o u n t V i e w s ( ) ; / / L i s t e n f o r v i s i b i l i t y c h a n g e d o c u m e n t . a d d E v e n t L i s t e n e r ( " v i s i b i l i t y c h a n g e " , c o u n t V i e w s , f a l s e ) ;
  60. BROWSERS' SUPPORT

  61. DESKTOP BROWSERS' SUPPORT Explorer Chrome Safari Firefox Opera 10+ 14+

    (-webkit) 33+ 6.1+ 10+ (-moz) 18+ 12.10+ 15+ (-webkit) 20+ Data updated to 21st June 2014
  62. MOBILE BROWSERS' SUPPORT Explorer Android Chrome Safari Firefox Opera 10+

    4.4+ 13+ (-webkit) 33+ 7.0+ 10+ (-moz) 18+ None Data updated to 21st June 2014
  63. HOW TO USE IT NOW visibly.js Visibility.js

  64. BATTERY STATUS API

  65. WHAT IT DOES? Provides information about the system's battery charge

    level Fires events about changes of the battery level or status
  66. USE CASES Slow down a process Save changes more frequently

    to prevent data loss Deny to start a critical and time consuming process
  67. PROPERTIES c h a r g i n g c

    h a r g i n g T i m e d i s c h a r g i n g T i m e l e v e l
  68. EVENTS c h a r g i n g c

    h a n g e c h a r g i n g t i m e c h a n g e d i s c h a r g i n g t i m e c h a n g e l e v e l c h a n g e
  69. EXAMPLE / / P r i n t i f

    b a t t e r y i s c h a r g i n g o r n o t c o n s o l e . l o g ( " T h e d e v i c e ' s b a t t e r y i s " + ( n a v i g a t o r . b a t t e r y . c h a r g i n g ? " " : " n o t " ) + " c h a r g i n g " ) ; / / P r i n t t h e c u r r e n t b a t t e r y l e v e l c o n s o l e . l o g ( " T h e l e v e l o f t h e b a t t e r y i s " + ( n a v i g a t o r . b a t t e r y . l e v e l ? ( n a v i g a t o r . b a t t e r y . l e v e l * 1 0 0 ) + " % " : " U N K N O W N " ) ) ;
  70. BROWSERS' SUPPORT

  71. DESKTOP BROWSERS' SUPPORT Explorer Chrome Safari Firefox Opera None None

    None 10+ (-moz) 16+ None Data updated to 21st June 2014
  72. MOBILE BROWSERS' SUPPORT Explorer Android Chrome Safari Firefox Opera None

    None None None 10+ (-moz) 16+ None Data updated to 21st June 2014
  73. HOW TO USE IT NOW NO POLYFILL AVAILABLE

  74. ...Better for Users

  75. VIBRATION API

  76. WHAT IT DOES? Provides tactile feedback

  77. USE CASES

  78. Vibrate on an explosion in a movie

  79. Vibrate when someone punches you in a fighting game

  80. Vibrate when in a racing game a car crashes

  81. METHODS The only method exposed is v i b r

    a t e ( ) .
  82. EXAMPLE / / V i b r a t e

    o n c e f o r 1 s e c o n d n a v i g a t o r . v i b r a t e ( 1 0 0 0 ) ; / / V i b r a t e t h r i c e . T w o t i m e s f o r 1 s e c o n d , w i t h a h a l f / / s e c o n d i n t e r v a l , a n d t h e n v i b r a t e f o r 2 s e c o n d s n a v i g a t o r . v i b r a t e ( [ 1 0 0 0 , 5 0 0 , 1 0 0 0 , 5 0 0 , 2 0 0 0 ] ) ; / / C a n c e l l i n g V i b r a t i o n s n a v i g a t o r . v i b r a t e ( 0 ) ;
  83. BROWSERS' SUPPORT

  84. DESKTOP BROWSERS' SUPPORT Explorer Chrome Safari Firefox Opera None 30+*

    32+ None 11+ (-moz) 16+ 17+* 19+ Data updated to 21st June 2014 * You have to activate the flag Experimental Web Platform features
  85. MOBILE BROWSERS' SUPPORT Explorer Android Chrome Safari Firefox Opera None

    4.4+ 30+* 32+ None 11+ (-moz) 16+ None Data updated to 21st June 2014 * You have to activate the flag Experimental Web Platform features
  86. HOW TO USE IT NOW NO POLYFILL AVAILABLE

  87. TO BE HONEST... mozVibrate-polyfill

  88. GETUSERMEDIA API

  89. WHAT IT DOES? Provides access to multimedia streams (video, audio,

    or both) from local devices
  90. USE CASES

  91. Real-time communication (chat)

  92. Recording tutorial or lesson for online courses

  93. Home or work surveillance

  94. METHODS The only method exposed is g e t U

    s e r M e d i a ( ) .
  95. EXAMPLE < v i d e o i d =

    " v i d e o " a u t o p l a y = " a u t o p l a y " c o n t r o l s = " t r u e " > < / v i d e o > < s c r i p t > v a r v i d e o = d o c u m e n t . g e t E l e m e n t B y I d ( " v i d e o " ) ; n a v i g a t o r . g e t U s e r M e d i a ( { v i d e o : t r u e , a u d i o : t r u e } , f u n c t i o n ( s t r e a m ) { v i d e o . s r c = s t r e a m ; v i d e o . p l a y ( ) ; } , f u n c t i o n ( e r r o r ) { c o n s o l e . l o g ( ' V i d e o c a p t u r e e r r o r : ' + e r r o r . c o d e ) ; } ) ; < / s c r i p t >
  96. BROWSERS' SUPPORT

  97. DESKTOP BROWSERS' SUPPORT Explorer Chrome Safari Firefox Opera None 21+

    (-webkit) None 17+ (-moz) 12+ 15+ (None) 18+ (-webkit) Data updated to 21st June 2014
  98. MOBILE BROWSERS' SUPPORT Explorer Android Chrome Safari Firefox Opera None

    None 21+ (-webkit) None 24+ (-moz) None Data updated to 21st June 2014
  99. HOW TO USE IT NOW getUserMedia.js

  100. TO LEARN MORE... ABOUT THESE AND OTHER APIS HTML5 API

    DEMOS https://github.com/AurelioDeRosa/HTML5-API-demos A repository I created and maintain. It contains a collection of demos that allows to play with some of the APIs introduced in HTML5.
  101. CONCLUSIONS Future of web development is bright ...but some browsers

    aren't prepared yet Focus on goals, not technologies Take care of performances Take care of devices' resources Take care of your users' experience
  102. THANK YOU!

  103. QUESTIONS?

  104. CONTACTS Website: Email: Twitter: www.audero.it a.derosa@audero.it @AurelioDeRosa