页面中开始时间与结束时间默认为上个月的第一天与最后一天及相关名词解释

(1)JS代码如下：

function showLastMonthFirstDayAndLastDay()
{
var Nowdate=new Date();
var s = Nowdate.getFullYear().toString() +'-'+ addzero(Nowdate.getMonth()) +'-'+ '01';
document.getElementById('txtBeginTime').value =s;

var Nowdate=new Date();
var MonthFirstDay=new Date(Nowdate.getYear(),Nowdate.getMonth(),1);
var MonthLastDay=new Date(MonthFirstDay-86400000);
var tempDay = MonthLastDay.toString().split(" ");
if(tempDay.length >1)
{
MonthLastDay = tempDay[2];
}
var MonthNextFirstDay=new Date(Nowdate.getYear(),Nowdate.getMonth()+1,1);
var e = Nowdate.getFullYear().toString() +'-'+ addzero(Nowdate.getMonth()) +'-'+ MonthLastDay;
document.getElementById('txtEndTime').value =e;
}

function addzero(v)
{
if (v < 10) return '0' + v;
return v.toString();
}

可参考：
http://bbs.csdn.net/topics/80366699
用javascript怎么取到当前月第一天、最后一天，本周第一天、最后一天

(2)

document.documentElement.scrollTop

整个html文档－－》根元素－－－》上滚动距离、

就是 向上滚出屏幕的页面的那段高度