How does js calculate last week and next week?

& lt% @ page language = " Java " import = " Java . util . * " page encoding = " utf-8 " % & gt；

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& lthead & gt

& ltmeta http-equiv = " Content-Type " Content = " text/html； charset=utf-8 " >

& lttitle & gt untitled document

& lt/head & gt；

& lt scripting language = "javascript">

Function setWeekTime(weekTime){

var time = new Array()；

if(weekTime=='last'){

time = getLastWeekDate()；

}

if(weekTime=='this'){

time = getThisWeekDate()； }

if(weekTime=='next'){

time = getNextWeekDate()； }

form 1 . Monday . value = time[0]；

form 1 . Tuesday . value = time[ 1]；

Form 1. Wednesday. value = time [2];

form 1 . Thursday . value = time[3]；

form 1 . Friday . value = time[4]；

form 1 . Saturday . value = time[5]；

form 1 . Sunday . value = time[6]； }

//Get Monday and weekend of this week.

Function getThisWeekDate(){

var now = new Date()；

var week = new Array()；

var current week = now . getday()；

if ( currentWeek == 0)

{

current week = 7；

} var Monday = now . gettime()-(current week- 1)* 24 * 60 * 60 * 1000； //Monday

var Tuesday = now . gettime()-(current week-2)* 24 * 60 * 60 * 1000； //Tuesday

Var Wednesday = now.gettime ()-(currentweek-3) * 24 * 60 * 60 *1000; //Wednesday

var Thursday = now . gettime()-(current week-4)* 24 * 60 * 60 * 1000； //Thursday

var Friday = now . gettime()-(current week-5)* 24 * 60 * 60 * 1000； //Friday

var Saturday = now . gettime()-(current week-6)* 24 * 60 * 60 * 1000； //Saturday

var Sunday = now . gettime()+(7-current week)* 24 * 60 * 60 * 1000； //Sunday

Week=weektoday (Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, Sunday);

Return week;

}

//Get Monday and weekend of last week.

Function getlasttweetdate () {

var now = new Date()；

var week = new Array()；

var current week = now . getday()；

if ( currentWeek == 0)

{

current week = 7；

}

var Monday = now . gettime()-(current week+6)* 24 * 60 * 60 * 1000； //Monday

var Tuesday = now . gettime()-(current week+5)* 24 * 60 * 60 * 1000； //Tuesday

Var Wednesday = now.gettime ()-(currentweek+4) * 24 * 60 * 60 *1000; //Wednesday

Var thursday = now.getTime()-(current week+3) * 24 * 60 * 60 *1000; //Thursday

var Friday = now . gettime()-(current week+2)* 24 * 60 * 60 * 1000； //Friday

var Saturday = now . gettime()-(current week+ 1)* 24 * 60 * 60 * 1000； //Saturday

var Sunday = now . gettime()-(current week)* 24 * 60 * 60 * 1000； //Sunday

Week=weektoday (Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, Sunday);

Return week;

}

//Get Monday to weekend of next week.

Function getNextWeekDate(){

var now = new Date()；

var week = new Array()；

var current week = now . getday()；

if ( currentWeek == 0)

{

current week = 7；

}

var Monday = now . gettime()-(current week-8)* 24 * 60 * 60 * 1000； //Monday

var Tuesday = now . gettime()-(current week-9)* 24 * 60 * 60 * 1000； //Tuesday

Var Wednesday = now.gettime ()-(Current Week-10) * 24 * 60 * 60 *1000; //Wednesday

var Thursday = now . gettime()-(current week- 1 1)* 24 * 60 * 60 * 1000； //Thursday

var Friday = now . gettime()-(current week- 12)* 24 * 60 * 60 * 1000； //Friday

var Saturday = now . gettime()-(current week- 13)* 24 * 60 * 60 * 1000； //Saturday

var Sunday = now . gettime()-(current week- 14)* 24 * 60 * 60 * 1000； //Sunday

Week=weektoday (Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, Sunday);

Return week;

}

Function weektoday (Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, Sunday) {var days = new array (); Var monday 1 = new date (Monday). toLocaleDateString()； //Monday

Var tuesday 1= new date (Tuesday). toLocaleDateString()； //Tuesday

Var wednesday 1 = new date (Wednesday). toLocaleDateString()； //Wednesday

Var thursday 1 = new date (Thursday). toLocaleDateString()； //Thursday

Var friday 1= new date (Friday). toLocaleDateString()； //Friday

Var Saturday 1 = new date (Saturday). toLocaleDateString()； //Saturday

Var sunday 1 = new date (Sunday). toLocaleDateString()； //Sunday

var new _ Monday = change time(Monday 1)；

var new _ Tuesday = change time(Tuesday 1)；

Var new _ Wednesday = changetime (Wednesday1);

var new _ Thursday = change time(Thursday 1)；

var new _ Friday = change time(Friday 1)；

var new _ Saturday = change time(Saturday 1)；

var new _ Sunday = change time(Sunday 1)； days[0]= new _ Monday；

Days[ 1]= new _ Tuesday;

Days[2]= new _ Wednesday;

days[3]= new _ Thursday；

days[4]= new _ Friday；

Days[5]= new _ Saturday;

days[6]= new _ Sunday；

Return days; }//date conversion (200565438+1October1= > 2005-1-0/)

Function change time (str) (

Varcuryear = str.substring (0，str . index of(' year '))；

Varcurvature = str。 Substring. index of ('year') + 1，str . index of(' month ')；

var cur day = str . substring(str . index of(' month ')+ 1，str . index of(' day ')；

if(curMonth & lt； 10){

curMonth = " 0 "+curMonth；

}

if(curDay & lt； 10){

curDay = " 0 "+curDay；

}

var return date = cur year+"-"+cur month+"-"+curDay；

ReturnDate

}

& lt/script & gt；

& ltbody & gt

& ltform name="form 1 " >

& lt table & gt

& lttr & gt

& lttd & gt Monday

& lttd & gt& ltinput type = " text " value = " " name = " Monday " >& lt/TD & gt；

& lttd & gt Tuesday

& lttd & gt& ltinput type = " text " value = " " name = " Tuesday " >& lt/TD & gt；

& lttd & gt Wednesday

& lt/TD & gt；< input type = "text" value = ""name = "Wednesday" ></TD >

& lt/tr & gt；

& lttr & gt

& lttd & gt Thursday

& lttd & gt& ltinput type = " text " value = " " name = " Thursday " >& lt/TD & gt；

& lttd & gt Friday

& lttd & gt& ltinput type = " text " value = " " name = " Friday " >& lt/TD & gt；

& lttd & gt Saturday

& lttd & gt& ltinput type = " text " value = " " name = " Saturday " >& lt/TD & gt；

& lt/tr & gt；

& lttr & gt

& lttd & gt Sunday

& lttd & gt& ltinput type = " text " value = " " name = " Sunday " >& lt/TD & gt；

& lt/tr & gt；

& lt/table & gt；

& lt table & gt

& lttr & gt

& lttd & gt& ltinput type = " button " value = " this week " onclick = " setweektime(' this ')" > & lt； /TD & gt；

& lttd & gt< input type = "button" value = "last week" onclick = "setweektime ('last')" > <; /TD & gt；

& lttd & gt& ltinput type = " button " value = " next week " onclick = " setweektime(' next ')" > & lt； /TD & gt； & lt/tr & gt；

& lt/table & gt；

& lt/form & gt；

& lt/body & gt；

& lt/html & gt；