flex判断当前日期是一年的第几周

/**
*
* 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); 

}

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