JS获取本周、本季度、本月、上月的开端日期、停止日期

var getdate=function(){    var now = new Date(); //当前日期    var nowDayOfWeek = now.getDay(); //今天本周的第几天    var nowDay = now.getDate(); //当前日    var nowMonth = now.getMonth(); //当前月    var nowYear = now.getYear(); //当前年    nowYear += (nowYear < 2000) ? 1900 : 0; //    var lastMonthDate = new Date(); //上月日期    lastMonthDate.setDate(1);    lastMonthDate.setMonth(lastMonthDate.getMonth()-1);    var lastMonth = lastMonthDate.getMonth();//上一月    //格式化日期：yyyy-MM-dd    function formatDate(date) {        var myyear = date.getFullYear();        var mymonth = date.getMonth()+1;        var myweekday = date.getDate();        if(mymonth < 10){            mymonth = "0" + mymonth;        }        if(myweekday < 10){            myweekday = "0" + myweekday;        }        return (myyear+"-"+mymonth + "-" + myweekday);    }    //获得某月的天数    function getMonthDays(myMonth){        var monthStartDate = new Date(nowYear, myMonth, 1);        var monthEndDate = new Date(nowYear, myMonth + 1, 1);        var days = (monthEndDate - monthStartDate)/(1000 * 60 * 60 * 24);        return days;    }    //获得本季度的开端月份    function getQuarterStartMonth(){        var quarterStartMonth = 0;        if(nowMonth<3){            quarterStartMonth = 0;        }        if(2<nowMonth && nowMonth<6){            quarterStartMonth = 3;        }        if(5<nowMonth && nowMonth<9){            quarterStartMonth = 6;        }        if(nowMonth>8){            quarterStartMonth = 9;        }        return quarterStartMonth;    }        //获得本周的开端日期    this.getWeekStartDate=function () {        var weekStartDate;        if(nowDayOfWeek==0){            weekStartDate = new Date(nowYear, nowMonth, nowDay - nowDayOfWeek+1-7);        }else{            weekStartDate = new Date(nowYear, nowMonth, nowDay - nowDayOfWeek+1);        }        return formatDate(weekStartDate);    }    //获得本周的停止日期    this.getWeekEndDate=function() {        var weekEndDate;        if(nowDayOfWeek==0){            weekEndDate = new Date(nowYear, nowMonth, nowDay + (6 - nowDayOfWeek)+1-7);        }else{            weekEndDate = new Date(nowYear, nowMonth, nowDay + (6 - nowDayOfWeek)+1);        }        return formatDate(weekEndDate);    }    //获得本月的开端日期    this.getMonthStartDate=function(){        var monthStartDate = new Date(nowYear, nowMonth, 1);        return formatDate(monthStartDate);    }    //获得本月的停止日期    this.getMonthEndDate=function(){        var monthEndDate = new Date(nowYear, nowMonth, getMonthDays(nowMonth));        return formatDate(monthEndDate);    }    //获得上月开端时候    this.getLastMonthStartDate=function(){        var lastMonthStartDate = new Date(nowYear, lastMonth, 1);        return formatDate(lastMonthStartDate);    }    //获得上月停止时候    this.getLastMonthEndDate=function(){        var lastMonthEndDate = new Date(nowYear, lastMonth, getMonthDays(lastMonth));        return formatDate(lastMonthEndDate);    }    //获得本季度的开端日期    this.getQuarterStartDate=function(){        var quarterStartDate = new Date(nowYear, getQuarterStartMonth(), 1);        return formatDate(quarterStartDate);    }    //获得本季度的停止日期    this.getQuarterEndDate=function(){        var quarterEndMonth = getQuarterStartMonth() + 2;        var quarterStartDate = new Date(nowYear, quarterEndMonth, getMonthDays(quarterEndMonth));        return formatDate(quarterStartDate);    }}//使用方法var mydate=new getdate();alert('本周时间: '+mydate.getWeekStartDate()+'--'+mydate.getWeekEndDate());