给一段代码帮一下我看一下关于日期函数为什么在2007年以前就可以成功准确地识别日期的星期,而2008年以后就不可以呢??

Question

function setdv(formobj,v){// oldv = formobj.options[formobj.selectedIndex].value;
// if (oldv=="non"){
for (i=0; i<formobj.length; i++){
if (formobj.options[i].value==v) {
formobj.options[i].selected = true;
break;
}
}
// }
}function setInitDate(datestr,yearobj,monthobj,dateobj){
setdv(yearobj,datestr.substring(2,4));
var month = datestr.substring(5,7);
var date = datestr.substring(8,10);
if(month.indexOf("0")==0){
month = month.substring(1);
}
if(date.indexOf("0")==0){
date = date.substring(1);
}
monthobj.options[month].selected = true;
dateobj.options[date].selected = true;
}//joly
function setDayNum(datestr_v){
 //alert(datestr_v.substring(0,4));
 //alert(datestr_v.substring(5,7));
 //alert(datestr_v.substring(5,7));
 var qq1=parseInt(datestr_v.substring(0,4));
 var qq2;
 if(parseInt(datestr_v.substring(5,6))==0){
     qq2=parseInt(datestr_v.substring(6,7))-1;
 }else{
 qq2=parseInt(datestr_v.substring(5,7))-1;
 }
 var qq3=parseInt(datestr_v.substring(8,10));
 //alert(qq2);
 var selectdate=new Date(qq1,qq2,qq3);
 var qq4=selectdate.getDay();
 if(qq4==6){
       document.form1.dayNum.value="星期日";
    }else if(qq4==0){
       document.form1.dayNum.value="星期一";
    }else if(qq4==1){
       document.form1.dayNum.value="星期二";
    }else if(qq4==2){
       document.form1.dayNum.value="星期三";
    }else if(qq4==3){
       document.form1.dayNum.value="星期四";
    }else if(qq4==4){
       document.form1.dayNum.value="星期五";
    }else if(qq4==5){
       document.form1.dayNum.value="星期六";
    }
   
 //GetDayOfWeek(datestr_v.substring(0,4),datestr_v.substring(5,7),datestr_v.substring(8,10));
 
 
 //alert(ii);
}

Answer 1

//joly
function setReDayNum(datestr_v){
 //alert(datestr_v.substring(0,4));
 //alert(datestr_v.substring(5,7));
 //alert(datestr_v.substring(5,7));
 var qq1=parseInt(datestr_v.substring(0,4));
 var qq2;
 if(parseInt(datestr_v.substring(5,6))==0){
     qq2=parseInt(datestr_v.substring(6,7))-1;
 }else{
 qq2=parseInt(datestr_v.substring(5,7))-1;
 }
 var qq3=parseInt(datestr_v.substring(8,10));
 //alert(qq2);
 var selectdate=new Date(qq1,qq2,qq3);
 var qq4=selectdate.getDay();
 if(qq4==6){
       document.form1.dayNum_Back.value="星期日";
    }else if(qq4==0){
       document.form1.dayNum_Back.value="星期一";
    }else if(qq4==1){
       document.form1.dayNum_Back.value="星期二";
    }else if(qq4==2){
       document.form1.dayNum_Back.value="星期三";
    }else if(qq4==3){
       document.form1.dayNum_Back.value="星期四";
    }else if(qq4==4){
       document.form1.dayNum_Back.value="星期五";
    }else if(qq4==5){
       document.form1.dayNum_Back.value="星期六";
    }
   
 //GetDayOfWeek(datestr_v.substring(0,4),datestr_v.substring(5,7),datestr_v.substring(8,10));
 
 
 //alert(ii);
}function GetDayOfWeek(y_v,m_v,d_v)
{
   var y=parseInt(y_v);var m=parseInt(m_v);var d=parseInt(d_v);
   alert(y);
   alert(m);
   alert(d);
  if((m==1)||(m==2))/*如果是一月或二月进行换算*/
   {
    m+=12;
    y--;
   }   var week=(d+2*m+3*Math.round((m+1)/5)+y+Math.round(y/4)-Math.round(y/100)+Math.round(y/400))%7;
   var weekstr = "";
   //alert(week);
   switch (week)
  {
     case 1: weekstr = "星期一"; break;
     case 2: weekstr = "星期二"; break;
     case 3: weekstr = "星期三"; break;
     case 4: weekstr = "星期四"; break;
     case 5: weekstr = "星期五"; break;
     case 6: weekstr = "星期六"; break;
     case 7: weekstr = "星期日"; break;
   }
   //alert(weekstr);
   document.form1.dayNum.value=weekstr; 
}function mkyearobj(objname){
document.write("<select name='",objname,"' size=1 class=itm onChange='setDateDayNum()'>");
document.write("<option selected value=non>&nbsp</option>");
yeart=0;
yearv=0;
year1="";
today=new Date();
yeart = today.getYear();
if (yeart<=147 && yeart>=100) {
yeart = yeart + 1900;
}
if (yeart<=2047 && yeart>=2000) {
yearv = yeart - 2000;
if (yearv<10) {
year1 = "0" + yearv;
}
document.write("<option value=",year1,">",yeart,"年</option>"); 
yeart = yeart + 1;
if (yeart<=2047 && yeart>=2000){
yearv = yearv + 1;
if (yearv<10) {
year1 = "0" + yearv;
}
document.write("<option value=",year1,">",yeart,"年</option>"); 
}
}
document.write("</select>");
}function mkyearobj_r(objname){
document.write("<select name='",objname,"' size=1 class=itm onChange='setDateDayNum_r()'>");
document.write("<option selected value=non>&nbsp</option>");
yeart=0;
yearv=0;
year1="";
today=new Date();
yeart = today.getYear();
if (yeart<=147 && yeart>=100) {
yeart = yeart + 1900;
}
if (yeart<=2047&& yeart>=2000) {
yearv = yeart - 2000;
if (yearv<10) {
year1 = "0" + yearv;
}
document.write("<option value=",year1,">",yeart,"年</option>"); 
yeart = yeart + 1;
if (yeart<=2047 && yeart>=2000){
yearv = yearv + 1;
if (yearv<10) {
year1 = "0" + yearv;
}
document.write("<option value=",year1,">",yeart,"年</option>"); 
}
}
document.write("</select>");
}

Answer 2

function mkmonthobj(objname){
document.write("<select name='",objname,"' size=1 class='itm'  onChange='setDateDayNum()'>");
document.write("<option value='non' selected>&nbsp</option>");
document.write("<option value='jan'>1月</option>");
document.write("<option value='feb'>2月</option>");
document.write("<option value='mar'>3月</option>");
document.write("<option value='apr'>4月</option>");
document.write("<option value='may'>5月</option>");
document.write("<option value='jun'>6月</option>");
document.write("<option value='jul'>7月</option>");
document.write("<option value='aug'>8月</option>");
document.write("<option value='sep'>9月</option>");
document.write("<option value='oct'>10月</option>");
document.write("<option value='nov'>11月</option>");
document.write("<option value='dec'>12月</option>");
document.write("</select>");
}function mkmonthobj_r(objname){
document.write("<select name='",objname,"' size=1 class='itm'  onChange='setDateDayNum_r()'>");
document.write("<option value='non' selected>&nbsp</option>");
document.write("<option value='jan'>1月</option>");
document.write("<option value='feb'>2月</option>");
document.write("<option value='mar'>3月</option>");
document.write("<option value='apr'>4月</option>");
document.write("<option value='may'>5月</option>");
document.write("<option value='jun'>6月</option>");
document.write("<option value='jul'>7月</option>");
document.write("<option value='aug'>8月</option>");
document.write("<option value='sep'>9月</option>");
document.write("<option value='oct'>10月</option>");
document.write("<option value='nov'>11月</option>");
document.write("<option value='dec'>12月</option>");
document.write("</select>");
}function mkdayobj(objname){document.write("<select name='",objname,"' size=1 class=itm  onChange='setDateDayNum()'>");
document.write("<option selected value=non>&nbsp</option>");
var datei = 1;
for(datei = 1; datei <= 31; datei++)
{
if (datei<10){
document.write("<option value=0",datei,">",datei,"日</option>"); 
}
else{
document.write("<option value=",datei,">",datei,"日</option>"); 
}
}
document.write("</select>");
}function mkdayobj_r(objname){
document.write("<select name='",objname,"' size=1 class=itm  onChange='setDateDayNum_r()'>");
document.write("<option selected value=non>&nbsp</option>");
var datei = 1;
for(datei = 1; datei <= 31; datei++)
{
if (datei<10){
document.write("<option value=0",datei,">",datei,"日</option>"); 
}
else{
document.write("<option value=",datei,">",datei,"日</option>"); 
}
}
document.write("</select>");
}function getdatenum(year,mon,day){
ret = 0;
year = remkyear(year);
ret = Date.parse(year+"/"+mon+"/"+day)
return ret;
}
function detecttoday(){
daynum=0;
year_v=0;
month_v=0;
day_v=0;
today=new Date();
year_v = today.getFullYear();
month_v = today.getMonth() + 1;
day_v = today.getDate();
daynum = Date.parse(year_v+"/"+month_v+"/"+day_v)
return daynum;
}
function getmonthnum(monv){
retnum=0;
switch (monv) {
case "jan": retnum=1; break;
case "feb": retnum=2; break;
case "mar": retnum=3; break;
case "apr": retnum=4; break;
case "may": retnum=5; break;
case "jun": retnum=6; break;
case "jul": retnum=7; break;
case "aug": retnum=8; break;
case "sep": retnum=9; break;
case "oct": retnum=10; break;
case "nov": retnum=11; break;
case "dec": retnum=12; break;
default: retnum=0; break;
}
return retnum;
}
function getdaynum(monv){
retnum=0;
if (!parseInt(monv,10)){retnum=0;}
else{retnum=parseInt(monv,10);}
return retnum;
}
function detectmondayok(year,mon,day){
rec = true;
year = remkyear(year);
bufDate = new Date(year,mon,0);
bufday = bufDate.getDate();
if (day > bufday){rec = false;}
return rec;
}
function remkyear(year){
if (year<1000){if (year<=37 && year>=0){year = year + 2000;}
else{if (year<=99 && year>=80){year = year + 1900;}}}
return year;
}