Unicorns Think Clockwise

Transcript

1. Unicorns think clockwise — Date & Time in web applications

   —

2. @polarblau

3. <plug>

4. pleaserevise.com

5. </plug>

6. Why?

7. None

8. 1 2 3 4 5 5

9. The top 5 reasons for ‘the pain‘

10. Time re–engineered

11. None
12. None
13. None
14. None

15. April 13, 2036

16. April 13, 2036

17. None

18. - 0 +

19. The earth day

20. Timezones

21. None

22. Daylight saving

23. None

24. The top 5 reasons for ‘the pain‘

25. Cultural differences 5

26. Humanity and a history of bad decisions 4

27. Confusing APIs 3

28. new Date(2036, 4, 13)

29. Tue May 13 2036 00:00:00 GMT+0300 (EEST)

30. var d = new Date(2036, 4, 13) d.setHours([…])

31. d.setHours(h, [m, [s, [ms]]])

32. Timezones and DST 2

33. UTC+05:45 (Nepal) UTC+12:45 (Chatham Islands) UTC+09:30 (Australia) UTC−04:30 (Venezuela)

34. *

35. * bad idea *

36. 1 “What he said!”

37. The top 5 no–no‘s

38. Don’t make assumptions 5

39. Don’t do more than necessary 4

40. Don’t make calculations on the client–side 3

41. Don’t compare local time with server time 2

42. Just avoid client time as much as possible 1

43. The top 5 do–do‘s

44. Remember: Offsets are not (always) defined as integer hours 5

45. 4 Standards

46. 2012-02-15T12:06Z

47. 2012-W07-3

48. 12d7h22m9s

49. (d > 0 && d < 3600) Activity within an

    hour in seconds:

50. 4217

51. 4217

52. 4217

53. 42 minutes + 17 seconds

54. Always persist in UTC 3

55. Unicorns Think Clockwise

56. Unicorns Think Clockwise

57. Unicorns Think Clockwise

58. Unicorns Think Clockwise

59. Client → Server

60. var apocalypse = new Date(2036, 4, 13); // “Tue May

    13 2036 00:00:00 GMT+0300 (EEST)”

61. $.getJSON(‘/api/rentals/availability’, { start: apocalypse }, renderAvailability);

62. Time.zone.parse(params[:start]) // Mon, 12 May 2036 21:00:00 UTC 00:00

63. apocalypse = Time.zone.parse(params[:start]) // Mon, 12 May 2036 21:00:00 UTC

    00:00

64. Server → Client

65. { start: apocalypse.iso8601 }.to_json // {"start":"2036-05-12T21:00:00Z"}

66. var apocalypseTS = Date.parse(response.start); var apocalypse = new Date(apocalypseTS); //

    “Tue May 13 2036 00:00:00 GMT+0300 (EEST)”

67. Convert to local time as late as possible (—if ever)

    2

68. 1 Relax (it’s just numbers)

69. d.getTime()

70. Helpers

71. Javascript moment.js XDate date.js

72. Ruby ice_cube timecop chronic delorean

73. Thanks!