javascript 年月日联动实现核心代码

var StartYear = 1980; 
var EndYear = 2500; function MonthAndDay() 
{ 
this.initDDL = function(objYear,objMonth,objDay,hidYear,hidMonth,hidDay) 
{ 
this.init(objYear,objMonth,objDay,hidYear,hidMonth,hidDay); 
this.SelectChange(objYear,objMonth,objDay,hidYear,hidMonth,hidDay); 
} 
this.init = function(objYear,objMonth,objDay,hidYear,hidMonth,hidDay) 
{ 
var year = document.getElementById(objYear); 
var month = document.getElementById(objMonth); 
var day = document.getElementById(objDay); 
var me=this; 
if(year.length == 1) 
{ 
year.options[0] = new Option("不限",""); 
for(var i = StartYear; i < EndYear; i++) 
{ 
year.options[year.length] = new Option(i,i); 
} 
} 
me.yearOptionsChange(document.all[objYear].value,objYear,objMonth,objDay); 
me.monthOptionsChange(document.all[objYear].value,document.getElementById(objMonth).value,objDay); 
} 
this.yearOptionsChange = function(selectValue,objYear,objMonth,objDay) 
{ 
var month = document.getElementById(objMonth); 
var day = document.getElementById(objDay); 
var me=this; 
month.length = 0; 
day.length = 0; 
month.options[0]=new Option("不限",''); 
day.options[0]=new Option("不限",''); 
if(selectValue == "") 
{ 
return ; 
} 
for(var i = 1; i < 13; i++) 
{ 
month.options[month.length] = new Option((i < 10 ? ("0" + i) : i),i); 
} 
me.monthOptionsChange(document.getElementById(objYear).value,document.getElementById(objMonth).value,objDay); 
} 
this.monthOptionsChange = function(yearSelectValue,monthSelectValue,objDay) 
{ 
var day = document.getElementById(objDay); 
var endDay; 
day.length = 0; 
day.options[0]=new Option("不限",''); 
if(monthSelectValue == "") 
{ 
return; 
} 
if((parseInt(yearSelectValue) % 400 == 0) || (parseInt(yearSelectValue) % 4 == 0 && parseInt(yearSelectValue) % 100 != 0)) 
{ 
if(parseInt(monthSelectValue) == "2") 
{ 
endDay = 29; 
} 
} 
else 
{ 
if(parseInt(monthSelectValue) == "2") 
{ 
endDay = 28; 
} 
} 
switch(parseInt(monthSelectValue)) 
{ 
case 1: 
case 3: 
case 5: 
case 7: 
case 8: 
case 10: 
case 12: 
endDay = 31; 
break; 
case 4: 
case 6: 
case 9: 
case 11: 
endDay = 30; 
break; 
} 
for(var i = 1; i <= endDay; i++) 
{ 
day.options[day.length] = new Option((i < 10 ? ("0" + i) : i),i); 
} 
} 
this.SelectChange = function(objYear,objMonth,objDay,hidYear,hidMonth,hidDay) 
{ 
var year = document.all[objYear]; 
var month = document.all[objMonth]; 
var day = document.all[objDay]; 
var me = this; 
year.onchange = function() 
{ 
me.yearOptionsChange(this.options[this.selectedIndex].value,objYear,objMonth,objDay); 
document.all[hidYear].value = this.options[this.selectedIndex].value; 
document.all[hidMonth].value = ""; 
document.all[hidDay].value = ""; 
} 
month.onchange = function() 
{ 
me.monthOptionsChange(document.all[hidYear].value,this.options[this.selectedIndex].value,objDay); 
document.all[hidMonth].value = this.options[this.selectedIndex].value; 
document.all[hidDay].value = ""; 
} 
day.onchange = function() 
{ 
document.all[hidDay].value = day.selectValue; 
} 
} 
}