moment.js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);
}