JS get this week, this quarter, this month, the last month's start date, end date

2. /**
4. * Get start date, end date for this week, quarter, month, month
6. */
8. var now = new Date (); //Current date
10. var nowdayofweek = Now.getday (); //The day of the week today
12. var nowday = Now.getdate (); //Current day
14. var nowmonth = Now.getmonth (); //Current Month
16. var nowyear = Now.getyear (); //When the year before
18. Nowyear + = (Nowyear < 2000)?  1900:0; //    
22. var lastmonthdate = new Date (); //Last month date
24. Lastmonthdate.setdate (1);
26. Lastmonthdate.setmonth (Lastmonthdate.getmonth ()-1);
28. var lastyear = Lastmonthdate.getyear ();
30. var lastmonth = Lastmonthdate.getmonth ();
34. Formatted Date: YYYY-MM-DD
36. function FormatDate (date) {
38. var myyear = Date.getfullyear ();
40. var mymonth = Date.getmonth () +1;
42. var myweekday = Date.getdate ();
46. if (Mymonth <) {
48. Mymonth = "0" + mymonth;
50. }
52. if (Myweekday <) {
54. Myweekday = "0" + myweekday;
56. }
58. return (myyear+"-" +mymonth + "-" + myweekday);
60. }
64. Get the number of days in a month
66. function Getmonthdays (mymonth) {
68. var monthstartdate = New Date (Nowyear, Mymonth, 1);
70. var monthenddate = New Date (nowyear, Mymonth + 1, 1);
72. var days = (monthenddate-monthstartdate)/(1000 * 60 * 60 * 24);
74. return days;
76. }
80. Get the start month of the quarter
82. function Getquarterstartmonth () {
84. var quarterstartmonth = 0;
86. if (nowmonth<3) {
88. Quarterstartmonth = 0;
90. }
92. if (2<nowmonth && nowmonth<6) {
94. Quarterstartmonth = 3;
96. }
98. if (5<nowmonth && nowmonth<9) {
100. Quarterstartmonth = 6;
102. }
104. if (nowmonth>8) {
106. Quarterstartmonth = 9;
108. }
110. return quarterstartmonth;
112. }
116. Get the start date for this week
118. function Getweekstartdate () {
120. var weekstartdate = New Date (Nowyear, Nowmonth, Nowday-nowdayofweek);
122. return FormatDate (weekstartdate);
124. }
128. Get the end date for this week
130. function Getweekenddate () {
132. var weekenddate = New Date (Nowyear, Nowmonth, Nowday + (6-nowdayofweek));
134. return FormatDate (weekenddate);
136. }
140. Get the start date for this month
142. function Getmonthstartdate () {
144. var monthstartdate = New Date (Nowyear, Nowmonth, 1);
146. return FormatDate (monthstartdate);
148. }
152. Get the end date for this month
154. function Getmonthenddate () {
156. var monthenddate = New Date (Nowyear, Nowmonth, Getmonthdays (Nowmonth));
158. return FormatDate (monthenddate);
160. }
164. Get start time last month
166. function Getlastmonthstartdate () {
168. var lastmonthstartdate = New Date (Nowyear, Lastmonth, 1);
170. return FormatDate (lastmonthstartdate);
172. }
176. Get last month end time
178. function Getlastmonthenddate () {
180. var lastmonthenddate = New Date (Nowyear, Lastmonth, Getmonthdays (Lastmonth));
182. return FormatDate (lastmonthenddate);
184. }
188. Get the start date for the quarter
190. function Getquarterstartdate () {
194. var quarterstartdate = New Date (Nowyear, Getquarterstartmonth (), 1);
196. return FormatDate (quarterstartdate);
198. }
202. Or the end date of the quarter
204. function Getquarterenddate () {
206. var quarterendmonth = getquarterstartmonth () + 2;
208. var quarterstartdate = New Date (Nowyear, Quarterendmonth, Getmonthdays (Quarterendmonth));
210. return FormatDate (quarterstartdate);
212. }

JS get this week, this quarter, this month, the last month's start date, end date