Javascript实现通过选择周数显示开始日和结束日的实现代码

//该方法有两个参数，date是给定的日期型参数，days是需要在该日期进行加减的天数。 
//例如，add(2010-10-01,-3)返回从2010-10-01这一天往前退3天的日期即2010-09-28 
function addDate(date,days){ 
var d=new Date(date); 
d.setDate(d.getDate()+days); 
var m=d.getMonth()+1; 
var tmpDate = d.getFullYear()+ "/" + m + "/" + d.getDate(); 
var resultDate = new Date(tmpDate); 
return resultDate; 
} 
//对选择的年月转换为YYYY-MM-dd的格式 
function changeDateFormat(DateIn){ 
var year = 0; 
var month = 0; 
var Day = 0; 
var currentDate = ""; 
year = DateIn.getYear(); 
month = DateIn.getMonth() + 1; 
Day = DateIn.getDate(); 
currentDate = year + "-"; 
if(month > 10){ 
currentDate = currentDate + month + "-"; 
}else{ 
currentDate = currentDate + "0" + month + "-"; 
} 
if(Day > 10){ 
currentDate = currentDate + Day; 
}else{ 
currentDate = currentDate + "0" + Day; 
} 
return currentDate; 
} 
//根据选择的周计算出本周的开始日和结束日 
function weekToDate(weekNumber,strWeekDay,dateIn){ 
//输出的开始日 var outputDate_1 = ""; 
//输出的结束日 var outputDate_2 = ""; 
var tmp_date= ""; 
//如果选择的年月1号这一天恰好为sunday，该周monday的日期为这一天的日期-6 
if(strWeekDay == '0'){ 
outputDate_1 = addDate(dateIn,-6); 
} 
//如果选择的年月1号这一天为monday,第二个参数设为0，以下以此类推。 
if(strWeekDay == '1'){ 
outputDate_1 = addDate(dateIn,0); 
} 
if(strWeekDay == '2'){ 
outputDate_1 = addDate(dateIn,-1); 
} 
if(strWeekDay == '3'){ 
outputDate_1 = addDate(dateIn,-2); 
} 
if(strWeekDay == '4'){ 
outputDate_1 = addDate(dateIn,-3); 
} 
if(strWeekDay == '5'){ 
outputDate_1 = addDate(dateIn,-4); 
} 
if(strWeekDay == '6'){ 
outputDate_1 = addDate(dateIn,-5); 
} 
if(weekNumber == '1'){ 
outputDate_2 = dateIn; 
} 
if(weekNumber == '2'){ 
outputDate_2 = addDate(outputDate_1,+7); 
} 
if(weekNumber == '3'){ 
outputDate_2 = addDate(outputDate_1,+14); 
} 
if(weekNumber == '4'){ 
outputDate_2 = addDate(outputDate_1,+21); 
} 
if(weekNumber == '5'){ 
outputDate_2 = addDate(outputDate_1,+28); 
} 
if(weekNumber == '1'){ 
//第1周的开始日结束日计算基点都是outputDate_1,因此单独判断 
document.getElementById("spnDate").value = changeDateFormat(outputDate_1); 
temp_date = addDate(outputDate_1,+6); 
document.getElementById("finishTime").value =changeDateFormat(temp_date); 
}else{ 
//第2周以后的开始日结束日都以outputDate_2为计算基点 
document.getElementById("spnDate").value = changeDateFormat(outputDate_2); 
temp_date = addDate(outputDate_2,+6); 
document.getElementById("finishTime").value =changeDateFormat(temp_date); 
} 
} 
function getFromToDateOfSelectedWeek(){ 
var year = document.getElementById("sltYear"); 
var optionYear=year.getElementsByTagName("option"); 
var strYear = "" ; 
for(var i=0;i<optionYear.length;++i) 
{ 
if(optionYear[i].selected){ 
strYear = optionYear[i].text; 
} 
} 
var month = document.getElementById("sltMonth"); 
var option = month.getElementsByTagName("option"); 
var strMonth = "" ; 
for(var i=0;i<option.length;++i) 
{ 
if(option[i].selected){ 
strMonth = option[i].text; 
} 
} 
//根据选择的年月，组合成yyyy/mm/01的日期字符串 
var sltDate_tmp_0 = strYear+ "/" + strMonth + "/" + "1"; 
//将日期字符串转换为日期型 
var sltDate_tmp_1 = new Date(sltDate_tmp_0); 
//取得该月1号所在的星期数 
var weekDay = sltDate_tmp_1.getDay(); 
//获取页面选择的周数 
var weekNumber = document.getElementById("weekNumber"); 
var optionWeek=weekNumber.getElementsByTagName("option"); 
var strWeek = "" ; 
var tmp_date= ""; 
var outputDate_1 = ""; 
var outputDate_2 = ""; 
for(var i=0;i<optionWeek.length;++i) 
{ 
if(optionWeek[i].selected){ 
strWeek = optionWeek[i].text; 
} 
} 
//选择第1周时计算该年月1号这一天为monday到sunday各种可能性，返回该周monday到sunday的日期 
//以下判断以此类推 
if(strWeek == '1'){ 
if(weekDay == '0'){ 
weekToDate(strWeek,'0',sltDate_tmp_1); 
} 
if(weekDay == '1'){ 
weekToDate(strWeek,'1',sltDate_tmp_1); 
} 
if(weekDay == '2'){ 
weekToDate(strWeek,'2',sltDate_tmp_1); 
} 
if(weekDay == '3'){ 
weekToDate(strWeek,'3',sltDate_tmp_1); 
} 
if(weekDay == '4'){ 
weekToDate(strWeek,'4',sltDate_tmp_1); 
} 
if(weekDay == '5'){ 
weekToDate(strWeek,'5',sltDate_tmp_1); 
} 
if(weekDay == '6'){ 
weekToDate(strWeek,'6',sltDate_tmp_1); 
} 
} 
if(strWeek == '2'){ 
if(weekDay == '0'){ 
weekToDate(strWeek,'0',sltDate_tmp_1); 
} 
if(weekDay == '1'){ 
weekToDate(strWeek,'1',sltDate_tmp_1); 
} 
if(weekDay == '2'){ 
weekToDate(strWeek,'2',sltDate_tmp_1); 
} 
if(weekDay == '3'){ 
weekToDate(strWeek,'3',sltDate_tmp_1); 
} 
if(weekDay == '4'){ 
weekToDate(strWeek,'4',sltDate_tmp_1); 
} 
if(weekDay == '5'){ 
weekToDate(strWeek,'5',sltDate_tmp_1); 
} 
if(weekDay == '6'){ 
weekToDate(strWeek,'6',sltDate_tmp_1); 
} 
} 
if(strWeek == '3'){ 
if(weekDay == '0'){ 
weekToDate(strWeek,'0',sltDate_tmp_1); 
} 
if(weekDay == '1'){ 
weekToDate(strWeek,'1',sltDate_tmp_1); 
} 
if(weekDay == '2'){ 
weekToDate(strWeek,'2',sltDate_tmp_1); 
} 
if(weekDay == '3'){ 
weekToDate(strWeek,'3',sltDate_tmp_1); 
} 
if(weekDay == '4'){ 
weekToDate(strWeek,'4',sltDate_tmp_1); 
} 
if(weekDay == '5'){ 
weekToDate(strWeek,'5',sltDate_tmp_1); 
} 
if(weekDay == '6'){ 
weekToDate(strWeek,'6',sltDate_tmp_1); 
} 
} 
if(strWeek == '4'){ 
if(weekDay == '0'){ 
weekToDate(strWeek,'0',sltDate_tmp_1); 
} 
if(weekDay == '1'){ 
weekToDate(strWeek,'1',sltDate_tmp_1); 
} 
if(weekDay == '2'){ 
weekToDate(strWeek,'2',sltDate_tmp_1); 
} 
if(weekDay == '3'){ 
weekToDate(strWeek,'3',sltDate_tmp_1); 
} 
if(weekDay == '4'){ 
weekToDate(strWeek,'4',sltDate_tmp_1); 
} 
if(weekDay == '5'){ 
weekToDate(strWeek,'5',sltDate_tmp_1); 
} 
if(weekDay == '6'){ 
weekToDate(strWeek,'6',sltDate_tmp_1); 
} 
} 
if(strWeek == '5'){ 
if(weekDay == '0'){ 
weekToDate(strWeek,'0',sltDate_tmp_1); 
} 
if(weekDay == '1'){ 
weekToDate(strWeek,'1',sltDate_tmp_1); 
} 
if(weekDay == '2'){ 
weekToDate(strWeek,'2',sltDate_tmp_1); 
} 
if(weekDay == '3'){ 
weekToDate(strWeek,'3',sltDate_tmp_1); 
} 
if(weekDay == '4'){ 
weekToDate(strWeek,'4',sltDate_tmp_1); 
} 
if(weekDay == '5'){ 
weekToDate(strWeek,'5',sltDate_tmp_1); 
} 
if(weekDay == '6'){ 
weekToDate(strWeek,'6',sltDate_tmp_1); 
} 
} 
}