JS date operations

1. Var now = new Date (); // current Date
2. Var nowDayOfWeek = now. getDay (); // the day of the week today
3. Var nowDay = now. getDate (); // current day
4. Var nowMonth = now. getMonth (); // current month
5. Var nowYear = now. getYear (); // current year
6. NowYear + = (nowYear <2000 )? 1900: 0 ;//
8. // Format the date: yyyy-MM-dd
9. Function formatDate (date ){
10. Var myyear = date. getFullYear ();
11. Var mymonth = date. getMonth () + 1;
12. Var myweekday = date. getDate ();
14. If (mymonth <10 ){
15. Mymonth = "0" + mymonth;
16. }
17. If (myweekday <10 ){
18. Myweekday = "0" + myweekday;
19. }
20. Return (myyear + "-" + mymonth + "-" + myweekday );
21. }
23. // Obtain the number of days in a month
24. Function getMonthDays (myMonth ){
25. Var monthStartDate = new Date (nowYear, myMonth, 1 );
26. Var monthEndDate = new Date (nowYear, myMonth + 1, 1 );
27. Var days = (monthEndDate-monthStartDate)/(1000*60*60*24 );
28. Return days;
29. }
31. // Obtain the start month of the current quarter
32. Function getQuarterStartMonth (){
33. Var quarterStartMonth = 0;
34. If (nowMonth <3 ){
35. QuarterStartMonth = 0;
36. }
37. If (2 <nowMonth & nowMonth <6 ){
38. QuarterStartMonth = 3;
39. }
40. If (5 <nowMonth & nowMonth <9 ){
41. QuarterStartMonth = 6;
42. }
43. If (nowMonth> 8 ){
44. QuarterStartMonth = 9;
45. }
46. Return quarterStartMonth;
47. }
49. // Obtain the start date of the week
50. Function getWeekStartDate (){
51. Var weekStartDate = new Date (nowYear, nowMonth, nowDay-nowDayOfWeek );
52. Return formatDate (weekStartDate );
53. }
55. // Obtain the end date of the week
56. Function getWeekEndDate (){
57. Var weekEndDate = new Date (nowYear, nowMonth, nowDay + (6-nowDayOfWeek ));
58. Return formatDate (weekEndDate );
59. }
61. // Obtain the start date of this month
62. Function getMonthStartDate (){
63. Var monthStartDate = new Date (nowYear, nowMonth, 1 );
64. Return formatDate (monthStartDate );
65. }
67. // Obtain the end date of this month
68. Function getMonthEndDate (){
69. Var monthEndDate = new Date (nowYear, nowMonth, getMonthDays (nowMonth ));
70. Return formatDate (monthEndDate );
71. }
73. // Obtain the start date of the current quarter
74. Function getQuarterStartDate (){
76. Var quarterStartDate = new Date (nowYear, getQuarterStartMonth (), 1 );
77. Return formatDate (quarterStartDate );
78. }
80. // Or end date of the current quarter
81. Function getQuarterEndDate (){
82. Var quarterEndMonth = getQuarterStartMonth () + 2;
83. Var quarterStartDate = new Date (nowYear, quarterEndMonth, getMonthDays (quarterEndMonth ));
84. Return formatDate (quarterStartDate );
85. }