javascript取日期问题

Question

<script language=javascript>
//今天
function showToDay()
{
var Nowdate=new Date();
M=Number(Nowdate.getMonth())+1
return Nowdate.getYear()+"-"+M+"-"+Nowdate.getDate();
}//本周第一天
function showWeekFirstDay()
{
var Nowdate=new Date();
var WeekFirstDay=new Date(Nowdate-(Nowdate.getDay()-1)*86400000);
return WeekFirstDay;
}
//本周最后一天
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;
}//本月第一天
function showMonthFirstDay()
{
var Nowdate=new Date();
var MonthFirstDay=new Date(Nowdate.getYear(),Nowdate.getMonth(),1);
return MonthFirstDay;
}
//本月最后一天
function showMonthLastDay()
{
var Nowdate=new Date();
var MonthNextFirstDay=new Date(Nowdate.getYear(),Nowdate.getMonth()+1,1);
var MonthLastDay=new Date(MonthNextFirstDay-86400000);
return MonthLastDay;
}
//上月第一天
function showPreviousFirstDay()
{
var MonthFirstDay=showMonthFirstDay()
return new Date(MonthFirstDay.getYear(),MonthFirstDay.getMonth()-1,1)
}
//上月最后一天
function showPreviousLastDay()
{
var MonthFirstDay=showMonthFirstDay();
return new Date(MonthFirstDay-86400000);
}
//上周第一天
function showPreviousFirstWeekDay()
{
var WeekFirstDay=showWeekFirstDay()
return new Date(WeekFirstDay-86400000*7)
}
//上周最后一天
function showPreviousLastWeekDay()
{
var WeekFirstDay=showWeekFirstDay()
return new Date(WeekFirstDay-86400000)
}
//上一天
function showPreviousDay()
{
var MonthFirstDay=new Date();
return new Date(MonthFirstDay-86400000);
}
//下一天
function showNextDay()
{
var MonthFirstDay=new Date();
return new Date((MonthFirstDay/1000+86400)*1000);
}
//下周第一天
function showNextFirstWeekDay()
{
var MonthFirstDay=showWeekLastDay()
return new Date((MonthFirstDay/1000+86400)*1000)
}
//下周最后一天
function showNextLastWeekDay()
{
var MonthFirstDay=showWeekLastDay()
return new Date((MonthFirstDay/1000+7*86400)*1000)
}
//下月第一天
function showNextFirstDay()
{
var MonthFirstDay=showMonthFirstDay()
return new Date(MonthFirstDay.getYear(),MonthFirstDay.getMonth()+1,1)
}
//下月最后一天
function showNextLastDay()
{
var MonthFirstDay=showMonthFirstDay()
return new Date(new Date(MonthFirstDay.getYear(),MonthFirstDay.getMonth()+2,1)-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=showPreviousFirstDay();
document.all.dateDate2.value=showPreviousLastDay();
}
if(num==5){
document.all.dateDate.value=showNextFirstDay();
document.all.dateDate2.value=showNextLastDay();
}
if(num==6){
document.all.dateDate.value=showPreviousFirstWeekDay();
document.all.dateDate2.value=showPreviousLastWeekDay();
}
if(num==7){
document.all.dateDate.value=showNextFirstWeekDay();
document.all.dateDate2.value=showNextLastWeekDay();
}
if(num==8){
document.all.dateDate.value=showPreviousDay();
document.all.dateDate2.value=showPreviousDay();
}
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="上一月" onclick=setDate(4)>&nbsp;
&nbsp;<input name=haha type=button value="本月" onclick=setDate(1)>&nbsp;
<input name=haha type=button value="下一月" onclick=setDate(5)>&nbsp;
<input name=haha type=button value="上一周" onclick=setDate(6)>&nbsp;
<input name=haha type=button value="本周" onclick=setDate(2)>&nbsp;
<input name=haha type=button value="下一周" onclick=setDate(7)>&nbsp;
<input name=haha type=button value="上一天" onclick=setDate(8)>&nbsp;
<input name=haha type=button value="今天" onclick=setDate(3)>&nbsp;
<input name=haha type=button value="下一天" onclick=setDate(9)>

Answer 1

<script language=javascript>
//全局变量存储操作后的当前月
var currentmonth,currentday
currentmonth=0
currentday=0
//今天
function showToDay()
{
var Nowdate=new Date();
M=Number(Nowdate.getMonth())+1
return Nowdate.getYear()+"-"+M+"-"+Nowdate.getDate();
}//本周第一天
function showWeekFirstDay()
{
var Nowdate=new Date();
var WeekFirstDay=new Date(Nowdate-(Nowdate.getDay()-1)*86400000);
return WeekFirstDay;
}
//本周最后一天
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;
}//本月第一天
function showMonthFirstDay(cases)
{
var Nowdate=new Date();
if(cases==""){
currentmonth=0
var MonthFirstDay=new Date(Nowdate.getYear(),Nowdate.getMonth(),1);
return MonthFirstDay;
}
if(cases=="nexts"){
var MonthFirstDay=new Date(Nowdate.getYear(),Nowdate.getMonth()+1+currentmonth,1);
return MonthFirstDay;
}
if(cases=="prev"){
var MonthFirstDay=new Date(Nowdate.getYear(),Nowdate.getMonth()-1+currentmonth,1);
return MonthFirstDay;
}
}
//本月最后一天
function showMonthLastDay(cases)
{
var Nowdate=new Date();
if(cases==""){
currentmonth=0
var MonthNextFirstDay=new Date(Nowdate.getYear(),Nowdate.getMonth()+1+currentmonth,1);
var MonthLastDay=new Date(MonthNextFirstDay-86400000);
return MonthLastDay;
}
if(cases=="nexts"){
var MonthNextFirstDay=new Date(Nowdate.getYear(),Nowdate.getMonth()+2+currentmonth,1);
var MonthLastDay=new Date(MonthNextFirstDay-86400000);
return MonthLastDay;
}
if(cases=="prev"){
var MonthNextFirstDay=new Date(Nowdate.getYear(),Nowdate.getMonth()+currentmonth,1);
var MonthLastDay=new Date(MonthNextFirstDay-86400000);
return MonthLastDay;
}
}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=showMonthFirstDay("nexts");
document.all.dateDate2.value=showMonthLastDay("nexts");
}
if(num==0){
document.all.dateDate.value=showMonthFirstDay("prev");
document.all.dateDate2.value=showMonthLastDay("prev");
}
}</script>
<input name=dateDate type=text>-><input name=dateDate2 type=text>
<input name=haha type=button value="上一月" onclick="setDate(0);currentmonth--">&nbsp;<input name=haha type=button value="本月" onclick=setDate(1)>&nbsp;<input name=haha type=button value="下一月" onclick="setDate(4);currentmonth++">&nbsp;
上一周&nbsp;<input name=haha type=button value="本周" onclick=setDate(2)>&nbsp;下一周&nbsp;
上一天&nbsp;<input name=haha type=button value="今天" onclick=setDate(3)>&nbsp;下一天
月份已经实现，周，请参考月份的做法，自己尝试。
：）如果实在不行 我可以帮忙

Answer 2

<script language=javascript>
//全局变量存储操作后的当前月
var currentmonth,currentweek,currentday
currentmonth=0
currentweek=0
currentday=0
//今天
function showToDay(cases)
{
var Nowdate=new Date();
if(cases==""){
currentday=0
M=Number(Nowdate.getMonth())+1
return Nowdate.getYear()+"-"+M+"-"+Nowdate.getDate();
}
if(cases=="nexts"){
return new Date(Nowdate-86400000*currentday);
}
if(cases=="prev"){
return new Date(Nowdate-86400000*currentday);
}
}//本周第一天
function showWeekFirstDay(cases)
{
var Nowdate=new Date();
if(cases==""){
    currentweek=0
var WeekFirstDay=new Date(Nowdate-(Nowdate.getDay()-1)*86400000);
return WeekFirstDay;
}
if(cases=="nexts"){
alert(currentweek);
var WeekFirstDay=new Date(Nowdate-(Nowdate.getDay()-1-7*currentweek)*86400000);
return WeekFirstDay;
}
if(cases=="prev"){
alert(currentweek);
var WeekFirstDay=new Date(Nowdate-(Nowdate.getDay()-1-7*currentweek)*86400000);
return WeekFirstDay;
}
}//本周最后一天
function showWeekLastDay(cases)
{
var Nowdate=new Date();
if(cases==""){
    currentweek=0
var WeekFirstDay=new Date(Nowdate-(Nowdate.getDay()-1)*86400000);
var WeekLastDay=new Date((WeekFirstDay/1000+6*86400)*1000);
return WeekLastDay;
}
if(cases=="nexts"){
var WeekFirstDay=new Date(Nowdate-(Nowdate.getDay()-1-7*currentweek)*86400000);
var WeekLastDay=new Date((WeekFirstDay/1000+6*86400)*1000);
return WeekLastDay;
}
if(cases=="prev"){
var WeekFirstDay=new Date(Nowdate-(Nowdate.getDay()-1-7*currentweek)*86400000);
var WeekLastDay=new Date((WeekFirstDay/1000+6*86400)*1000);
return WeekLastDay;
}
}//本月第一天
function showMonthFirstDay(cases)
{
var Nowdate=new Date();
if(cases==""){
currentmonth=0
var MonthFirstDay=new Date(Nowdate.getYear(),Nowdate.getMonth(),1);
return MonthFirstDay;
}
if(cases=="nexts"){
var MonthFirstDay=new Date(Nowdate.getYear(),Nowdate.getMonth()+1+currentmonth,1);
return MonthFirstDay;
}
if(cases=="prev"){
var MonthFirstDay=new Date(Nowdate.getYear(),Nowdate.getMonth()-1+currentmonth,1);
return MonthFirstDay;
}
}
//本月最后一天
function showMonthLastDay(cases)
{
var Nowdate=new Date();
if(cases==""){
currentmonth=0
var MonthNextFirstDay=new Date(Nowdate.getYear(),Nowdate.getMonth()+1+currentmonth,1);
var MonthLastDay=new Date(MonthNextFirstDay-86400000);
return MonthLastDay;
}
if(cases=="nexts"){
var MonthNextFirstDay=new Date(Nowdate.getYear(),Nowdate.getMonth()+2+currentmonth,1);
var MonthLastDay=new Date(MonthNextFirstDay-86400000);
return MonthLastDay;
}
if(cases=="prev"){
var MonthNextFirstDay=new Date(Nowdate.getYear(),Nowdate.getMonth()+currentmonth,1);
var MonthLastDay=new Date(MonthNextFirstDay-86400000);
return MonthLastDay;
}
}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=showMonthFirstDay("nexts");
document.all.dateDate2.value=showMonthLastDay("nexts");
}
if(num==5){
document.all.dateDate.value=showMonthFirstDay("prev");
document.all.dateDate2.value=showMonthLastDay("prev");
}
if(num==6){
document.all.dateDate.value=showWeekFirstDay("nexts");
document.all.dateDate2.value=showWeekLastDay("nexts");
}
if(num==7){
document.all.dateDate.value=showWeekFirstDay("prev");
document.all.dateDate2.value=showWeekLastDay("prev");
}
if(num==8){
document.all.dateDate.value=showToDay("nexts");
document.all.dateDate2.value=showToDay("nexts");
}
if(num==9){
document.all.dateDate.value=showToDay("prev");
document.all.dateDate2.value=showToDay("prev");
}
}</script>
<input name=dateDate type=text>-><input name=dateDate2 type=text>
<input name=haha type=button value="上一月" onclick="setDate(5);currentmonth--">&nbsp;<input name=haha type=button value="本月" onclick=setDate(1)>&nbsp;<input name=haha type=button value="下一月" onclick="setDate(4);currentmonth++">&nbsp;
<input name=haha type=button value="上一周" onclick="currentweek--;setDate(7)">&nbsp;<input name=haha type=button value="本周" onclick=setDate(2)>&nbsp;<input name=haha type=button value="下一周" onclick="currentweek++;setDate(6)">&nbsp;
<input name=haha type=button value="上一天" onclick="currentday++;setDate(9)">&nbsp;<input name=haha type=button value="今天" onclick=setDate(3)>&nbsp;<input name=haha type=button value="下一天" onclick="currentday--;setDate(8)">