如何判断一个月有多少个星期？以及每个月的起始和终结的星期几？

[hwoarangzk]

应该从哪里下手？

[hwoarangzk]

我试试

[kslion]

写了下，供参考：

function YearMonth(year, month) {
	this.year = year; 
	this.month = month;
	
	this.isLeapYear = new Date(year,1,29).getDate() < 29 ? false : true;
}

YearMonth.prototype = {
	days:[31,28,31,30,31,30,31,31,30,31,30,31
	],
	//该月有几天
	getDaysCount : function() {
		return (this.isLeapYear && this.month==2 ) ? 29 : this.days[this.month-1];			
	},
	//该月有几周
	getWeeksCount : function() {
		var firstday = new Date(this.year, this.month, 1).getDay(); 
		var firstWeekDays = 6-firstday;
		var remainDays = this.getDaysCount()-firstWeekDays;
		
		return Math.ceil(remainDays / 7 + 1); 
	},
	//第一天是周几
	getFirstDayInfo : function() {
		var first = new Date(this.year, this.month, 1);
		
		return this.getWeek(first.getDay());
	},
	//最后天是周几
	getLastDayInfo : function() {
		var last = (this.isLeapYear && this.month==2 ) ? 29 : this.days[month-1];
		last = new Date(this.year, this.month, last);
		
		return this.getWeek(first.getDay());
	},
	//判断周几
	getWeek : function(index) {
		switch(index) {
			case 0 : return 'sun'; break;
			case 1 : return 'mon'; break;
			case 2 : return 'tue'; break;
			case 3 : return 'wed'; break;
			case 4 : return 'thu'; break;
			case 5 : return 'fri'; break;
			case 6 : return 'sat'; break;
			default: alert('invalid');
		}
	}
}

window.onload = function() {
	
	var ym = new YearMonth(2009, 9);
	var days = ym.getDaysCount();
	var weeks = ym.getWeeksCount(); 
	
}

[stayalive]

getDay
返回值
0 星期天
1 星期一
2 星期二
3 星期三
4 星期四
5 星期五
6 星期六

[mykelly6]

遍历那个月的每一天，用getDay看每天是星期几，然后各种加减乘除计数器就能得到你的答案了

var myDate = new Date();
myDate.getYear();       				//current year(2位)
myDate.getFullYear();   				//current full year(4位,1970-now)
myDate.getMonth();      				//current month(0-11,0-->1月)
myDate.getDate();       				//current day(1-31)
myDate.getDay();         				//current weekday(0-6,0-->日曜日)
myDate.getTime();       				//current time(Milliseconds form 1970.1.1)
myDate.getHours();       				//current hour(0-23)
myDate.getMinutes();     				//current minute(0-59)
myDate.getSeconds();     				//current second(0-59)
myDate.getMilliseconds();   			//current Milliseconds(0-999)
myDate.toLocaleDateString();     		//get current date
var mytime=myDate.toLocaleTimeString();     //get current time
myDate.toLocaleString( );       		//get current date and time

[qqm05]

<%
Dim a,b
a=CDate("2009-9-6")

b=WeekDayName(Weekday(a))
response.write b


%>

[亥亥]

asp判断星期比较好

[ACMAIN_CHM]

getDay(); 判断一下1号和下个月1号的数，然后再天数除7

[cloudgamer]

var y = 2010, m = 10;

alert( "星期数" + Math.ceil((new Date(y, m, 0).getDate() + new Date(y, m - 1, 1).getDay()) / 7) );
alert( "开始星期" + new Date(y, m - 1, 1).getDay() );
alert( "结束星期" + new Date(y, m, 0).getDay() );

[qqm05]

<%
Dim a
a=CDate("2010-9-6")

response.write Year(a) & "年" & Month(a) & "月，共有" & days(a) & "天<br>"
response.write Year(a) & "年"&Month(a) & "月，共有" & weeks(a) & "个星期<br>"
write_fl_Weekday a

Function days(d)
	days=DateDiff("d",a,Dateadd("m",1,d))
End function
Function weeks(d)
	ds=days(d)
	If ds Mod 7>0 Then 
		weeks=Int(ds/7)+1
	Else
		weeks=Int(ds/7)
	End if
End Function
Function write_fl_Weekday(a)
	f=CDate(Year(a) & "-" & Month(a) & "-1")
	l=DateAdd("d",f,days(a)-1)
	response.write "本月第一天("& f &")是:" & WeekDayName(Weekday(f)) & "<br>"
	response.write "本月最后一天("& l &")是:" & WeekDayName(Weekday(l)) & "<br>"
	
End Function 
%>

[tray123]

路过！！学习！！！

[licip]

你循环一下，不就什么都有了。这个关键是看每一个月的最后一天。特别是二月