下面代码是亲测且可用的，计算上一周时间确实费了不少劲，因为要考虑跨月和跨年的情况：

$("#report").change(function () {
    var report = $(this).val();
    var beginTime = '';
    var endTime = '';
    var myDate = new Date();

    if (report == 'daily') {
　　　　 // 获取昨天
        myDate.setTime(myDate.getTime()-24*3600*1000);
        beginTime = myDate.getFullYear()+"-" + (myDate.getMonth()+1) + "-" + myDate.getDate();
        endTime = beginTime;
    } else if (report == 'weekly') {
        // 获取上一周的开始和结束时间
        var weekDate = new Date(myDate.getTime() - 7 * 24 * 3600 * 1000);// 计算开始时间用
        var weekDate2 = new Date(myDate.getTime() - 7 * 24 * 3600 * 1000);// 计算结束时间用

        var day = weekDate.getDay();
        var time = weekDate.getDate()-day+(day===0?-6:1);

        var startDate = new Date(weekDate.setDate(time));
        beginTime = startDate.getFullYear()+'-'+(startDate.getMonth()+1)+'-'+startDate.getDate();
        var endDate = new Date(weekDate2.setDate(time+6));
        endTime = endDate.getFullYear()+'-'+(endDate.getMonth()+1)+'-'+endDate.getDate();

    } else if (report == 'monthly') {
        // 获取上一月的开始和结束时间
        var year = myDate.getFullYear();
        var month = myDate.getMonth();
        if (month === 0) {
            month = 12;
            year = year-1;
        } else if (month < 10) {
            month = '0'+month;
        }
        var monthDate = new Date(year, month, 0);
        beginTime = year+'-'+month+'-01';
        endTime = year+'-'+month+'-'+monthDate.getDate();

    } else if (report == 'annual') {
        // 获取去年的开始和结束时间
        var year = myDate.getFullYear()-1;
        beginTime = year+'-01-01';
        endTime = year+'-12-31';
    }

    $("#begintime").val(beginTime);
    $("#endtime").val(endTime);

});