var date = new Date();

    var year = date.getFullYear();

    var month = (date.getMonth() + 1) > 10 ? date.getMonth() + 1 : '0' + (date.getMonth() + 1);

    var day = date.getDate() > 10 ? date.getDate() : '0' + date.getDate();

    var nowdatestr = year + "-" + month + "-" + day;

    var darr1="";

    //近3天

    function getDay(day) {

        var today = new Date();

        var targetday_milliseconds = today.getTime() + 1000 * 60 * 60 * 24 * day;

        today.setTime(targetday_milliseconds); //注意，这行是关键代码

        var tYear = today.getFullYear();

        var tMonth = today.getMonth();

        var tDate = today.getDate();

        tMonth = doHandleMonth(tMonth + 1);

        tDate = doHandleMonth(tDate);

        return tYear + "-" + tMonth + "-" + tDate;

    }

    function doHandleMonth(month) {

        var m = month;

        if (month.toString().length == 1) {

            m = "0" + month;

        }

        return m;

    }

    //近7天

    $("#sevenday").click(function () {

        var oneweekdate = new Date(date - 6 * 24 * 3600 * 1000);

        var year1 = oneweekdate.getFullYear();

        var month1 = oneweekdate.getMonth() + 1 > 10 ? oneweekdate.getMonth() + 1 : '0' + oneweekdate.getMonth() + 1;

        var day1 = oneweekdate.getDate() > 10 ? oneweekdate.getDate() : '0' + oneweekdate.getDate();

        $("#begin_time").val(year1 + "-" + month1 + "-" + day1);

    });

    //近1个月

    $("#onemonth").click(function () {

        $("#begin_time").val(getPreMonthDay(nowdatestr, 1));

    });

    //近3个月

    $("#threemonth").click(function () {

        $("#begin_time").val(getPreMonthDay(nowdatestr, 3));

    });

    //获取当前日期前N个月的日期

    function getPreMonthDay(date, monthNum) {

        var dateArr = date.split('-');

        console.log(dateArr)

        var year = dateArr[0]; //获取当前日期的年份

        var month = dateArr[1]; //获取当前日期的月份

        var day = dateArr[2]; //获取当前日期的日

        var days = new Date(year, month, 0);

        days = days.getDate(); //获取当前日期中月的天数

        var year2 = year;

        var month2 = parseInt(month) - monthNum;

        if (month2 <= 0) {

            year2 = parseInt(year2) - parseInt(month2 / 12 == 0 ? 1 : parseInt(month2) / 12);

            month2 = 12 - (Math.abs(month2) % 12);

        }

        var day2 = day;

        var days2 = new Date(year2, month2, 0);

        days2 = days2.getDate();

        if (day2 > days2) {

            day2 = days2;

        }

        if (month2 < 10) {

            month2 = '0' + month2;

        }

        var t2 = year2 + '-' + month2 + '-' + day2;

        return t2;

    }

  //重写toLocaleString把时间戳转换为想要的格式

    Date.prototype.toLocaleString = function () {

        return this.getFullYear().toString() + "-" + (this.getMonth() + 1).toString() + "-" + this.getDate().toString() + "   " + this.getHours().toString() + ":" + this.getMinutes().toString() + ":" + this.getSeconds().toString();

    };