WAT JavaScript Date

Transcript

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5. “Wat” is a variant of the English word “what” that is often used to express confusion or disgust, much like its better known acronym “WTF,” short for “what the fuck.” http://knowyourmeme.com/memes/wat
6. 0.1 + 0.2
7. 0.1 + 0.2 // 0.30000000000000004
16. https://www.destroyallsoftware.com/talks/wat
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18. // Firefox latest new Date("2005-07-08");
19. // Firefox latest new Date("2005-07-08"); // Date 2005-07-08T00:00:00.000Z
20. // Firefox latest new Date("2005-07-08"); // Date 2005-07-08T00:00:00.000Z new Date("2005/07/08");
21. // Firefox latest new Date("2005-07-08"); // Date 2005-07-08T00:00:00.000Z new Date("2005/07/08"); // Date 2005-07-07T16:00:00.000Z
23. // Firefox latest new Date("2005-07-08"); // Date 2005-07-08T00:00:00.000Z // July 8th 00:00 UTC new Date("2005/07/08"); // Date 2005-07-07T16:00:00.000Z // July 8th 00:00 local time
24. // Firefox latest new Date("2005-07-08"); // Date 2005-07-08T00:00:00.000Z // July 8th 00:00 UTC new Date("2005/07/08"); // Date 2005-07-07T16:00:00.000Z // July 8th 00:00 local time (Date.parse("2005-07-08") - Date.parse("2005/07/08")) / 36e5 // 8 hours
25. // Firefox latest new Date("2005-07-08"); // Date 2005-07-08T00:00:00.000Z // July 8th 00:00 UTC new Date("2005/07/08"); // Date 2005-07-07T16:00:00.000Z // July 8th 00:00 local time (Date.parse("2005-07-08") - Date.parse("2005/07/08")) / 36e5 // 8 hours // Chrome latest new Date("2005-07-08");
26. // Firefox latest new Date("2005-07-08"); // Date 2005-07-08T00:00:00.000Z // July 8th 00:00 UTC new Date("2005/07/08"); // Date 2005-07-07T16:00:00.000Z // July 8th 00:00 local time (Date.parse("2005-07-08") - Date.parse("2005/07/08")) / 36e5 // 8 hours // Chrome latest new Date("2005-07-08"); // Fri Jul 08 2005 08:00:00 GMT+0800 (CST) // July 8th 00:00 local time
28. // Firefox var theday = new Date(2017, 2, 3, 0, 0, 0, 0);
29. // Firefox var theday = new Date(2017, 2, 3, 0, 0, 0, 0); // Date 2017-03-02T16:00:00.000Z
31. // Firefox var theday = new Date(2017, 2, 3, 0, 0, 0, 0); // Date 2017-03-02T16:00:00.000Z // 2 -> March, 0 based
32. // Firefox var theday = new Date(2017, 2, 3, 0, 0, 0, 0); // Date 2017-03-02T16:00:00.000Z // 2 -> March, 0 based // UTC Time: 03/02 16:00 // UTC+8 Time: 03/03 00:00
33. // Firefox var theday = new Date(2017, 2, 3, 0, 0, 0, 0); // Date 2017-03-02T16:00:00.000Z // 2 -> March, 0 based // UTC Time: 03/02 16:00 // UTC+8 Time: 03/03 00:00 theday.getDate() // 3 theday.getUTCDate() // 2
34. // Firefox var theday = new Date(2017, 2, 3, 0, 0, 0, 0); // Date 2017-03-02T16:00:00.000Z // 2 -> March, 0 based // UTC Time: 03/02 16:00 // UTC+8 Time: 03/03 00:00 theday.getDate() // 3 theday.getUTCDate() // 2 new Date(2017, 2, 3, 8, 0, 0, 0); // Date 2017-03-03T00:00:00.000Z
35. // Firefox var theday = new Date(2017, 2, 3, 0, 0, 0, 0); // Date 2017-03-02T16:00:00.000Z // 2 -> March, 0 based // UTC Time: 03/02 16:00 // UTC+8 Time: 03/03 00:00 theday.getDate() // 3 theday.getUTCDate() // 2 new Date(2017, 2, 3, 8, 0, 0, 0); // Date 2017-03-03T00:00:00.000Z new Date(Date.UTC(2017, 2, 3, 8, 0, 0, 0)); // Date 2017-03-03T08:00:00.000Z
36. var d = new Date(2016, 12, 31); d.setMonth(d.getMonth() + 1); d.toISOString();
37. new Date('0'); new Date(0); new Date(0, 0); new Date(0, 0, 0);
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41. https://twitter.com/BrendanEich/status/481939099138654209
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43. https://www.cs.princeton.edu/courses/archive/fall97/cs461/jdkdocs/relnotes/deprecatedlist.html
44. https://www.cs.princeton.edu/courses/archive/fall97/cs461/jdkdocs/relnotes/deprecatedlist.html
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48. // momentjs var thedate = moment("20170131", "YYYYMMDD");
49. // momentjs var thedate = moment("20170131", "YYYYMMDD"); thedate.add(2, 'months').format();
50. // momentjs var thedate = moment("20170131", "YYYYMMDD"); thedate.add(2, 'months').format(); // "2017-03-31T00:00:00+08:00"
51. // momentjs var thedate = moment("20170131", "YYYYMMDD"); thedate.add(2, 'months').format(); // "2017-03-31T00:00:00+08:00" thedate.add(1, 'months').add(1, 'months').format();
52. // momentjs var thedate = moment("20170131", "YYYYMMDD"); thedate.add(2, 'months').format(); // "2017-03-31T00:00:00+08:00" thedate.add(1, 'months').add(1, 'months').format(); // "2017-03-28T00:00:00+08:00"
53. // momentjs var thedate = moment("20170131", "YYYYMMDD"); thedate.add(2, 'months').format(); // "2017-03-31T00:00:00+08:00" thedate.add(1, 'months').add(1, 'months').format(); // "2017-03-28T00:00:00+08:00" thedate.add(1, 'months').format(); // "2017-02-28T00:00:00+08:00"
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58. // moment.js moment.tz("2014-02-09T02:30", "US/Pacific").format() // "2014-02-09T02:30:00-08:00"
59. // moment.js moment.tz("2014-02-09T02:30", "US/Pacific").format() // "2014-02-09T02:30:00-08:00" moment.tz("2014-03-09T02:30", "US/Pacific").format() // "2014-03-09T03:30:00-07:00"
60. // moment.js moment.tz("2014-02-09T02:30", "US/Pacific").format() // "2014-02-09T02:30:00-08:00" moment.tz("2014-03-09T02:30", "US/Pacific").format() // "2014-03-09T03:30:00-07:00" // Daylight Saving Time
61. https://time.is/en/PT
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73. import addMonths from 'date-fns/add_months' var thedate = new Date(2017, 0, 31); addMonths(thedate, 2);
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77. var thedate = LocalDate.parse('2017-01-31').atStartOfDay(); var after2m = thedate.plusMonths(2); after2m.toString(); // "2017-03-31T00:00" var sixtydays = Duration.ofDays(60); thedate.plus(sixtydays).toString(); // "2017-04-01T00:00" ZonedDateTime.now(ZoneId.of('Europe/Paris')).toString(); // "2017-02-04T17:01:15.846+01:00[Europe/Paris]"
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84. https://github.com/tc39/proposal-temporal
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88. var ldt = new temporal.LocalDateTime(2017, 12, 31, 23, 59); var addHours = new temporal.LocalDateTime( 2017, 12, 31, 23, 00).add(2, 'hours'); var zdt = new temporal.ZonedDateTime('America/New_York', 2017, 12, 31, 23, 59);
89. var ldt = new CivilDateTime(2017, 12, 31, 23, 59); var addHours = new CivilDateTime(2017, 12, 31, 23, 00) .add(2, 'hours'); var zdt = ldt.withZone(‘America/New_York');
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