实例,
判断当前日期是一年的第几周
private function weekOfYear(yyyy:Number,mm:Number,dd:Number):Number{
var myDate =new Date(yyyy, mm - 1, dd);
var startDate = new Date(yyyy,0,1);
var diff = myDate.valueOf() - startDate.valueOf();
var d = Math.round(diff/86400000);
return Math.ceil((d + ((startDate.getDay() + 1) - 1)) / 7);