通过某年某月第几个星期，获取这个星期的开始时间和结束时间

Question

javascript获取。

Answer 1

<script>
    function getStEtDay(year,month,indexOfWeek){
        var dt=new Date(year+"/"+month+"/01");
        var firstDayOfYear=new Date(year+"/01/01").getDay();
        var val=dt.valueOf()+Math.round(((indexOfWeek-1)*7-firstDayOfYear)*24*3600*1000);
        dt=new Date(val);
        var st=new Date(val-6*24*3600*1000);
        alert("第"+indexOfWeek+"周第一天"+st.toLocaleString())
        alert("最后一天"+dt.toLocaleString());
    }
    getStEtDay("2009","1",20);//举例,这里是20周
</script>

Answer 2

function getfirstday(yyyy,mm,wknum){
        var date=new Date(yyyy,mm-1,1);
        date.setDate(7*(wknum-1)-date.getDay());
        return date;
    }
    var startdate=getfirstday(2008,1,3);
    document.write(startdate);

Answer 3

改一点点就行了<script>
    function getStEtDay(year,month,indexOfWeek){
        var dt=new Date(year+"/"+month+"/01");
        var firstDayOfMonth=dt.getDay();
        var val=dt.valueOf()+Math.round((indexOfWeek*7-firstDayOfMonth)*24*3600*1000);
        dt=new Date(val);
        var st=new Date(val-6*24*3600*1000);
        alert("第"+indexOfWeek+"周第一天"+st.toLocaleString())
        alert("最后一天"+dt.toLocaleString());
    }
    getStEtDay("2009","10",5);//10月第5周
</script>

Answer 4

math.Round() 这里的作用是转换成整型,其他函数不懂的可以去查查google