利用JS实现点击上一周或下一周却换

1.页面加载显示当前年份的第几周

 效果如图：

html代码：

  <font size="2" color="black">
     <input id="btnweek5" type="button" class="btn" value="上周" onclick="EduCommission.GetLastWeek()" />
      <span id="year"></span><span>第</span><span id="week"></span><span>周</span>
      <input id="btnweek6" type="button" value="下周" class="btn" onclick="EduCommission.GetNextWeek()" />
  </font>

JS代码：

    var date = new Date();
    nowyear = date.getFullYear();
    nowweek = EduCommission.TheWeek(date);
    $("#year").text(nowyear);
    $("#week").text(nowweek - 1);

  

//本周 EduCommission.TheWeek = function (now) {

    var totalDays = 0;    

    var years = now.getYear();

    if (years < 1000)  

       years += 1900;   

  var days = new Array(12);   

   days[0] = 31;   

   days[2] = 31;  

   days[3] = 30;  

   days[4] = 31;   

   days[5] = 30;   

   days[6] = 31;  

   days[7] = 31;  

   days[8] = 30;  

   days[9] = 31;  

   days[10] = 30;

    days[11] = 31;

    if (Math.round(now.getYear() / 4) == now.getYear() / 4)

    {  days[1] = 29;     }

    else { days[1] = 28;}  

   if (now.getMonth() == 0)

     {  

       totalDays = totalDays + now.getDate(); 

     }

  else {  

       var curMonth = now.getMonth();

       for (var count = 1; count <= curMonth; count++) {  

       totalDays = totalDays + days[count - 1];         }  

       totalDays = totalDays + now.getDate();     }    

      var week = Math.round(totalDays / 7) + 1;    

      return week; }

 2.点击上一周或下一周时：

//点击上一周

EduCommission.GetLastWeek = function () {   

var y = $("#year").text();

    var week = $("#week").text();

    if (week == 1) {

        $("#year").text(y - 1);

        var strdate = y - 1 + "-12-31";

        var date = new Date(Date.parse(strdate.replace(/-/g, "/")));

        var lastyearweek = EduCommission.TheWeek(date);

        $("#week").text(lastyearweek);     }    

   else {        

      $("#week").text(week - 1);

     }  }；

//点击下一周

EduCommission.GetNextWeek = function () {

    var y = $("#year").text();  

    var week = $("#week").text();

    if (y < nowyear) {

        var strdate = y + "-12-31";

        var date = new Date(Date.parse(strdate.replace(/-/g, "/")));              

        var weekcount = EduCommission.TheWeek(date);

        if (week == weekcount) {

            $("#year").text(parseInt(y) + 1);

            $("#week").text(1);

            }

       else {

            $("#week").text(parseInt(week) + 1);  

             }

      else {

        $("#week").text(parseInt(week) + 1);

            } 

}；