给定日期，取得是当年的第几周

function getTodayWeekNo(){
	/*
	//将当前年的第一天默认为第一周的第一天
    var today = new Date();
    var beginDay = new Date(today.getFullYear(),0,1);
    var weekNo = parseInt((today.getTime() - beginDay.getTime())/(7*24*60*60*1000))
    return weekNo+1 ;
    */
    
    
    //周日为一周的第一天，周六为一周的最后一天
    var todayDate = new Date();   //今天
    var beginDate = new Date(todayDate.getFullYear(), 0, 1);  //今年第一天
    var n = beginDate.getDay();   //今年第一天星期几
    var dayCount = Math.ceil((todayDate - beginDate)/(24*60*60*1000));//今年第几天
    if(n != 0){
    	var m = parseInt("0654321".charAt(n));
    	weekNo = Math.ceil((dayCount-m)/7) + 1;
    }else{
    	weekNo = Math.ceil(dayCount/7);
    }
    return weekNo;
}