A small example of js to get the week number and day of the week of a specified date_javascript skills

function getNowFormatDate(theDate) 
{ 
var day = theDate; 
var Year = 0; 
var Month = 0; 
var Day = 0; 
var CurrentDate = ""; 
// 初始化时间 
Year= day.getFullYear();// ie火狐下都可以 
Month= day.getMonth()+1; 
Day = day.getDate(); 
CurrentDate += Year + "-"; 
if (Month >= 10 ) 
{ 
CurrentDate += Month + "-"; 
} 
else 
{ 
CurrentDate += "0" + Month + "-"; 
} 
if (Day >= 10 ) 
{ 
CurrentDate += Day ; 
} 
else 
{ 
CurrentDate += "0" + Day ; 
} 
return CurrentDate; 
} 

function isInOneYear(_year,_week){ 
if(_year == null || _year == '' || _week == null || _week == ''){ 
return true; 
} 
var theYear = getXDate(_year,_week,4).getFullYear(); 
if(theYear != _year){ 
return false; 
} 
return true; 
} 

// 获取日期范围显示 
function getDateRange(_year,_week){ 
var beginDate; 
var endDate; 
if(_year == null || _year == '' || _week == null || _week == ''){ 
return ""; 
} 
beginDate = getXDate(_year,_week,4); 
endDate = getXDate(_year,(_week - 0 + 1),5); 
return getNowFormatDate(beginDate) + " 至 "+ getNowFormatDate(endDate); 
} 

// 这个方法将取得某年(year)第几周(weeks)的星期几(weekDay)的日期 
function getXDate(year,weeks,weekDay){ 
// 用指定的年构造一个日期对象，并将日期设置成这个年的1月1日 
// 因为计算机中的月份是从0开始的,所以有如下的构造方法 
var date = new Date(year,"0","1"); 

// 取得这个日期对象 date 的长整形时间 time 
var time = date.getTime(); 

// 将这个长整形时间加上第N周的时间偏移 
// 因为第一周就是当前周,所以有:weeks-1,以此类推 
// 7*24*3600000 是一星期的时间毫秒数,(JS中的日期精确到毫秒) 
time+=(weeks-1)*7*24*3600000; 

// 为日期对象 date 重新设置成时间 time 
date.setTime(time); 
return getNextDate(date,weekDay); 
} 
// 这个方法将取得 某日期(nowDate) 所在周的星期几(weekDay)的日期 
function getNextDate(nowDate,weekDay){ 
// 0是星期日,1是星期一,... 
weekDay%=7; 
var day = nowDate.getDay(); 
var time = nowDate.getTime(); 
var sub = weekDay-day; 
if(sub <= 0){ 
sub += 7; 
} 
time+=sub*24*3600000; 
nowDate.setTime(time); 
return nowDate; 
}

//日期处理 
function dateRange(){ 
var _year = $("#_year").val(); 
var _week = $("#_week").val(); 
if(isInOneYear(_year,_week)){ 
var showDate = getDateRange(_year,_week); 
$("#_dateRange_import").html(showDate); 
} else{ 
alert(_year+"年无"+_week+"周，请重新选择"); 
$("#_week").val(""); 
} 
}