Calculate the range of last month, next month, last week, and next week.

<Script language = JavaScript>
// Today
Function showtoday ()
{
VaR nowdate = new date ();
M = Number (nowdate. getmonth () + 1
Return nowdate. getyear () + "-" + M + "-" + nowdate. getdate ();
}

// The first day of the week
Function showweekfirstday ()
{
VaR nowdate = new date ();
VaR weekfirstday = new date (nowdate-(nowdate. getday ()-1) * 86400000 );
Return weekfirstday;
}
// Last day of the week
Function showweeklastday ()
{
VaR nowdate = new date ();
VaR weekfirstday = new date (nowdate-(nowdate. getday ()-1) * 86400000 );
VaR weeklastday = new date (weekfirstday/1000 + 6*86400) * 1000 );
Return weeklastday;
}

// The first day of the month
Function showmonthfirstday ()
{
VaR nowdate = new date ();
VaR monthfirstday = new date (nowdate. getyear (), nowdate. getmonth (), 1 );
Return monthfirstday;
}
// Last day of the month
Function showmonthlastday ()
{
VaR nowdate = new date ();
VaR monthnextfirstday = new date (nowdate. getyear (), nowdate. getmonth () + 1, 1 );
VaR monthlastday = new date (MonthNextFirstDay-86400000 );
Return monthlastday;
}
// The first day of last month
Function showpreviusfirstday ()
{
VaR monthfirstday = showmonthfirstday ()
Return new date (monthfirstday. getyear (), monthfirstday. getmonth ()-1, 1)
}
// Last day of last month
Function showpreviuslastday ()
{
VaR monthfirstday = showmonthfirstday ();
Return new date (MonthFirstDay-86400000 );
}
// The first day of last week
Function showpreviusfirstweekday ()
{
VaR weekfirstday = showweekfirstday ()
Return new date (WeekFirstDay-86400000 * 7)
}
// Last day of last week
Function showpreviuslastweekday ()
{
VaR weekfirstday = showweekfirstday ()
Return new date (WeekFirstDay-86400000)
}
// Last day
Function showpreviusday ()
{
VaR monthfirstday = new date ();
Return new date (MonthFirstDay-86400000 );
}
// Next day
Function shownextday ()
{
VaR monthfirstday = new date ();
Return new date (monthfirstday/1000 + 86400) * 1000 );
}
// The first day of next week
Function shownextfirstweekday ()
{
VaR monthfirstday = showweeklastday ()
Return new date (monthfirstday/1000 + 86400) * 1000)
}
// Last day of next week
Function shownextlastweekday ()
{
VaR monthfirstday = showweeklastday ()
Return new date (monthfirstday/1000 + 7*86400) * 1000)
}
// The first day of next month
Function shownextfirstday ()
{
VaR monthfirstday = showmonthfirstday ()
Return new date (monthfirstday. getyear (), monthfirstday. getmonth () + 1, 1)
}
// Last day of next month
Function shownextlastday ()
{
VaR monthfirstday = showmonthfirstday ()
Return new date (monthfirstday. getyear (), monthfirstday. getmonth () + 86400000)
}
Function date. Prototype. tostring (){
Return this. getfullyear () + "-" + (this. getmonth () + 1) + "-" + this. getdate ();
}
Function setdate (Num ){
If (num = 1 ){
Document. All. datedate. value = showmonthfirstday ();
Document. All. datedate2.value = showmonthlastday ();
}
If (num = 2 ){
Document. All. datedate. value = showweekfirstday ();
Document. All. datedate2.value = showweeklastday ();
}
If (num = 3 ){
Document. All. datedate. value = showtoday ();
Document. All. datedate2.value = showtoday ();
}
If (num = 4 ){
Document. All. datedate. value = showpreviusfirstday ();
Document. All. datedate2.value = showpreviuslastday ();
}
If (num = 5 ){
Document. All. datedate. value = shownextfirstday ();
Document. All. datedate2.value = shownextlastday ();
}
If (num = 6 ){
Document. All. datedate. value = showpreviusfirstweekday ();
Document. All. datedate2.value = showpreviuslastweekday ();
}
If (num = 7 ){
Document. All. datedate. value = shownextfirstweekday ();
Document. All. datedate2.value = shownextlastweekday ();
}
If (num = 8 ){
Document. All. datedate. value = showpreviusday ();
Document. All. datedate2.value = showpreviusday ();
}
If (num = 9 ){
Document. All. datedate. value = shownextday ();
Document. All. datedate2.value = shownextday ();
}
}

</SCRIPT>
<Input name = datedate type = text>-> <input name = datedate2 type = text>
& Nbsp; <input name = Haha type = button value = "last month" onclick = setdate (4)> & nbsp;
& Nbsp; <input name = Haha type = button value = "this month" onclick = setdate (1)> & nbsp;
<Input name = Haha type = button value = "next month, January" onclick = setdate (5)> & nbsp;
<Input name = Haha type = button value = "previous week" onclick = setdate (6)> & nbsp;
<Input name = Haha type = button value = "this week" onclick = setdate (2)> & nbsp;
<Input name = Haha type = button value = "next week" onclick = setdate (7)> & nbsp;
<Input name = Haha type = button value = "Last Day" onclick = setdate (8)> & nbsp;
<Input name = Haha type = button value = "today" onclick = setdate (3)> & nbsp;
<Input name = Haha type = button value = "next day" onclick = setdate (9)>