最近在一个项目中遇到一个查询页面，其中一个查询条件是根据选择的年份、月以及周数显示选择的该周从几号到几号，这样一个需求。在网上搜索了一下，有类似的但是没有完全一样的，只好自己动手。思路是首先取得所选择的该年月1号这一天是星期几，然后算出这一周中周一的日期。
以此为基点，第1周的结束日即为这一天加6，第2周的开始日为这一天加7，结束日为这一天加13，以此类推，直到推算出第5周的开始日和结束日。
具体代码如下：
//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()+ "https://www.jb51.net/" + m + "https://www.jb51.net/" + 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+ "https://www.jb51.net/" + strMonth + "https://www.jb51.net/" + "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); } } }