原生js实现日期联动

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。