本文基于react-native

本人在用react-native写一个关于课程表的APP时需要课程表按照日期周期显示，网上查了许多方法，都没有达到自己想要的效果，根据一些方法的参考，再根据自己思维写出自己想要的效果如下图所示

获取每月有几周（注：从第一个周一开始算该月第一周）

    getWeeks(year, month) {

        var d = new Date();

        // 该月第一天

        d.setFullYear(year, month-1, 1);

        var w1 = d.getDay();

        if (w1 == 0) w1 = 7;

        // 该月天数

        d.setFullYear(year, month, 0);

        var dd = d.getDate();

        // 第一个周一

        let d1;

        if (w1 != 1) d1 = 7 - w1 + 2;

        else d1 = 1;

        let week_count = Math.ceil((dd-d1+1)/7);

        return week_count;

    }

根据年月周获取该周从周一到周日的日期

    getWeekTime(year, month,weekday) {

        var d = new Date();

        // 该月第一天

        d.setFullYear(year, month-1, 1);

        var w1 = d.getDay();

        if (w1 == 0) w1 = 7;

        // 该月天数

        d.setFullYear(year, month, 0);

        var dd = d.getDate();

        // 第一个周一

        let d1;

        if (w1 != 1) d1 = 7 - w1 + 2;

        else d1 = 1;

        var monday = d1+(weekday-1)*7;

        var sunday = monday + 6;

        var from = year+"-"+month+"-"+monday;

        var to;

        if (sunday <= dd) {

            to = year+"-"+month+"-"+sunday;

        } else {

            d.setFullYear(year, month-1, sunday);

            let days=d.getDate();

            to = d.getFullYear()+"-"+(d.getMonth()+1)+"-"+days;

        }

        console.log(weekday+" 从" + from + " 到 " + to + "");

    }

获取每月第几周的周一的日期

    getMondayTime(year, month,weekday) {

        var d = new Date();

        // 该月第一天

        d.setFullYear(year, month-1, 1);

        var w1 = d.getDay();

        if (w1 == 0) w1 = 7;

        // 该月天数

        d.setFullYear(year, month, 0);

        var dd = d.getDate();

        // 第一个周一

        let d1;

        if (w1 != 1) d1 = 7 - w1 + 2;

        else d1 = 1;

        var monday = d1+(weekday-1)*7;

        return monday;

    }

获取周一的日期

    getMonDate() {

        var d=new Date(),

            day=d.getDay(),

            date=d.getDate();

        if(day==1)

            return d;

        if(day==0)

            d.setDate(date-6);

        else

            d.setDate(date-day+1);

        return d;

    }

获得周期名字

    getDayName(day) {

        var day=parseInt(day);

        if(isNaN(day) || day<0 || day>6)

            return false;

        var weekday=["周日","周一","周二","周三","周四","周五","周六"];

        return weekday[day];

    }

获得当前日期在当月第几周

    //不包括跟上个月重合的部分

    getMonthWeek(a, b, c) {

        var date = new Date(a, parseInt(b) - 1, c), w = date.getDay(), d = date.getDate();

        return Math.ceil(

            (d + 6 - w) / 7

        );

    }

获取当月最后一天日期

    getLastDay(year,month) {

        var new_year = year;    //取当前的年份

        var new_month = month++;//取下一个月的第一天，方便计算（最后一天不固定）

        if(month>12) {

            new_month -=12;        //月份减

            new_year++;            //年份增

        }

        var new_date = new Date(new_year,new_month,1);                //取当年当月中的第一天

        return (new Date(new_date.getTime()-1000*60*60*24)).getDate();//获取当月最后一天日期

    }

根据当前日期获取该天所在周，若该月1号不是周一，获取该月第一周的周一日期，小于该日期的归为上个月最后一周

    //当前日期几月第几周

    showDate(){

        var that=this;

        var d=this.getMonDate();

        var ds=new Date();

        var arr=[];

        for(var i=0; i<7; i++) {

            let weekDay=this.getDayName(d.getDay());

            let date=d.getDate()+'日';

            if(weekDay=='周一'){

                let beginTime=ds.getFullYear()+'-'+(d.getMonth()+1)+'-'+d.getDate();

                that.state.beginTime = beginTime;

            }

            if(weekDay=='周日'){

                let endTime=ds.getFullYear()+'-'+(d.getMonth()+1)+'-'+d.getDate();

                that.state.endTime = endTime;

            }

            arr.push({weekDay:weekDay,date:date});

            d.setDate(d.getDate()+1);

        }

        let month=ds.getMonth()+1;

        let weeks=this.getMonthWeek(ds.getFullYear(),month,ds.getDate())-1;

        //每月周一日期

        let oneDate=that.getMondayTime(ds.getFullYear(),month,1);

        if(ds.getDate()<oneDate){

            month=ds.getMonth();

            weeks=this.getWeeks(ds.getFullYear(),month);

        }

        console.log('month:',month,'weeks:',weeks);

        this.setState({

            list:arr,

            yearDate:ds.getFullYear(),

            monthDate:month,

            month:ds.getMonth()+1,

            monthWeek:'第'+weeks+'周',

            theMonthWeek:'第'+weeks+'周'

        });

    }