moment.js轻松实现获取当前日期是当年的第几周

/**
     * 实现当前日期是当年的第几周,再向前和向后推几周
     * js数组保存当前日期的前后两周(共五周的数据)
     * */
    var initSearchMajorChanges = function(){
        //实现当前日期是当年的第几周,再向前和向后推几周,js数组保存当前日期的前后两周(共五周的数据)
        var vv='2015-02-07';
        var vNowDate=moment(new moment(vv).format("YYYY-MM-DD"));//.add('month',0).add('days',-1);
        var vWeekOfDay=moment(vNowDate).format("E");//算出这周的周几
        var vWeekOfDays=7-vWeekOfDay-1;
        var vStartDate=moment(vNowDate).add('days',vWeekOfDays);
        var vEndDate=moment(vNowDate).add('days',-vWeekOfDay);
        var vStartDateNew=moment(vStartDate).add('days',7*$scope.gWeeks);
        var vEndDateNew=moment(vEndDate).add('days',-(7*$scope.gWeeks));
        //var vYearAndWeek=moment(vStartDate).format("YYYY")+'-'+moment(vStartDate).format("WW");
        searchMajorChanges(vStartDateNew,vEndDateNew);
    }