JavaScript 计算当前日期为本月第几周

<script language="javascript">
var getMonthWeek = function (a, b, c) { 
/* 
a = d = 当前日期 
b = 6 - w = 当前周的还有几天过完(不算今天) 
a + b 的和在除以7 就是当天是当前月份的第几周 
*/ 
var date = new Date(a, parseInt(b) - 1, c), w = date.getDay(), d = date.getDate(); 
return Math.ceil( 
(d + 6 - w) / 7 
); 
};
var getYearWeek = function (a, b, c) { 
/* 
date1是当前日期 
date2是当年第一天 
d是当前日期是今年第多少天 
用d + 当前年的第一天的周差距的和在除以7就是本年第几周 
*/ 
var date1 = new Date(a, parseInt(b) - 1, c), date2 = new Date(a, 0, 1), 
d = Math.round((date1.valueOf() - date2.valueOf()) / 86400000); 
return Math.ceil( 
(d + ((date2.getDay() + 1) - 1)) / 7 
); 
}; 
today=new Date();//获取当前时间
var y = today.getYear();
var m = today.getMonth()+1;
var d = today.getDate();
document.write( "今天是",m,"月的第 ", getMonthWeek(y, m, d), " 周" ); 
</script>