月份的判定，由于涉及到过多了判定条件，如果用if else会大大降低性能，建议用switch 语法
代码如下：
getDays:function(year,month){
// var aDay = [31,28|29,31,30,31,30,31,31,30,31,30,31];
// 二月份的天数数据处理
var FedDays = year%4==0?29:28,
returnDays = '';
var month = month<10?month = '0'+month:month.toString();
switch(month){
case '01':
case '03':
case '05':
case '07':
case '08':
case '10':
case '12': returnDays = 31;break;
case '04':
case '06':
case '09':
case '11': returnDays = 30;break;
case '02': returnDays = FedDays;break;
}
return returnDays;
}
完整的源代码：
/* author:laoguoyong
------------------------------
日期三级联动,范围选择
------------------------------
参数
* [String] targets:'#year,#month,#day' ；年，月，日的id
* [String] range:'2013-02-03,2019-09-21'；范围，正确格式为xxxx-xx-xx
----为了节省代码，请传入正确的日期范围参数
----错误示范：
（1）range:'2013-02-03,2019-9-21' 是不对的，注意日期格式
（2）range:'2013-02-03' 是不对的，请输入完整的范围之值
（3）range:'2013-02-03,2016-02-30' 是不对的，2月没有30天
（3）range:'2013-02-03,2011-02-30' 是不对的，范围错误了
*
*/
function GySetDate(opt){
//elem
var targets = opt.targets.split(',');
this.eYear = this.getId(targets[0].slice(1));
this.eMonth = this.getId(targets[1].slice(1));
this.eDay = this.getId(targets[2].slice(1));
if(!this.eYear||!this.eMonth||!this.eDay) return;
//范围值
var r = opt.range.indexOf(','),
aStarts = opt.range.slice(0,r).split('-'), // 转为：['2013','05','20']
aEnds = opt.range.slice(r+1,opt.range.length).split('-'); // 转为：['2018','08','20']
//Number类型
this.startYear = parseInt(aStarts[0],10);
this.startMonth = parseInt(aStarts[1],10);
this.startDay = parseInt(aStarts[2],10);
this.endYear = parseInt(aEnds[0],10);
this.endMonth = parseInt(aEnds[1],10);
this.endDay = parseInt(aEnds[2],10);
this.init();
}
GySetDate.prototype = {
init:function(){
var _that = this;
// 初始化日期
this.setYears({'start':this.startYear,'end':this.endYear});
this.setMonths({'start':this.startMonth});
this.setDays({'year':this.startYear,'month':this.startMonth,'start':this.startDay});
// 年选择
this.eYear.onchange = function(){
var year = parseInt(this.value);
switch(true){
case (year == _that.startYear):{
_that.setMonths({'start':_that.startMonth});
_that.setDays({'year':_that.startYear,'month':_that.startMonth,'start':_that.startDay});
};break;
case (year == _that.endYear):{
_that.setMonths({'start':1,'end':_that.endMonth});
if(_that.endMonth>1){
_that.setDays({'year':_that.endYear,'month':1,'start':1});
}else{
_that.setDays({'year':_that.endYear,'month':1,'start':1,'end':_that.endDay});
}
};break;
default:{
_that.setMonths({'start':1});
_that.setDays({'start':1,'year':year,'month':1});
}
}
}
// 月选择
this.eMonth.onchange = function(){
var year = parseInt(_that.eYear.options[_that.eYear.selectedIndex].value),
month = parseInt(this.value);
switch(true){
case (year==_that.endYear&&month==_that.endMonth):{
_that.setDays({'start':1,'year':year,'month':month,'end':_that.endDay});
};break;
case (year==_that.startYear&&month==_that.startMonth):{
_that.setDays({'year':_that.startYear,'month':_that.startMonth,'start':_that.startDay});
};break;
default:{
_that.setDays({'start':1,'year':year,'month':month});
}
}
}
},
/*设置年，月，日
----------------------------------
参数值都为Number类型
*/
// 参数 {'start':xx,'end':xxx}
setYears:function(opt){
this.eYear.innerHTML = '';
for(var n=opt.start;n<=opt.end;n++){
this.eYear.add(new Option(n,n));
}
},
// 参数 {'start':xx,'end':xxx}
// 参数 'end' 为可选，忽略，则开始到12月
setMonths:function(opt){
this.eMonth.innerHTML = '';
var months = opt.end || 12;
for(var n=opt.start;n<=months;n++){
if(n<10) n = '0'+n;
this.eMonth.add(new Option(n,n));
}
},
// 参数 {'start':xx,'year':xxx,'month':xx,'star':xx,'end':xxx}
// 参数 'end' 为可选，忽略，则开始到本月底（根据月份判断的）
setDays:function(opt){
this.eDay.innerHTML = '';
var days = opt.end || this.getDays(opt.year,opt.month);
for(var n=opt.start;n<=days;n++){
if(n<10) n = '0'+n;
this.eDay.add(new Option(n,n));
}
},
/* 根据 年，月，返回正确的天数，如 2016-2，返回是29天（润年）
--------------------------------------------------------------
参数值都为Number类型
*/
getDays:function(year,month){
// var aDay = [31,28|29,31,30,31,30,31,31,30,31,30,31];
// 二月份的天数数据处理
var FedDays = year%4==0?29:28,
returnDays = '';
var month = month<10?month = '0'+month:month.toString();
switch(month){
case '01':
case '03':
case '05':
case '07':
case '08':
case '10':
case '12': returnDays = 31;break;
case '04':
case '06':
case '09':
case '11': returnDays = 30;break;
case '02': returnDays = FedDays;break;
}
return returnDays;
},
/*工具辅助函数
----------------------------------
*/
getId:function(id){
return document.getElementById(id);
}
}
效果展示图：
效果还不错吧，小伙伴们自己美化下，使用到自己的项目中去吧。