var todayStart = new Date(new Date().toLocaleDateString());

var oneday = 1000 * 60 * 60 * 24;
var todayEnd = new Date(todayStart.getTime() + oneday - 1);

var monthStart = new Date((new Date(new Date().setDate(1)).toLocaleDateString()));

var date=new Date();
var currentMonth = date.getMonth();//八月份，currentMonth=7
var nextMonth = ++currentMonth;
var nextMonthFirstDay=new Date(date.getFullYear(),nextMonth,1);//下个月的第一天零点
monthEnd = new Date(nextMonthFirstDay.getTime()-1);//将下个月第一天的零点毫秒数减1

Date.prototype.format = function(fmt){ 
  var o = { 
    "M+" : this.getMonth()+1,                 //月份 
    "d+" : this.getDate(),                    //日 
    "h+" : this.getHours(),                   //小时 
    "m+" : this.getMinutes(),                 //分 
    "s+" : this.getSeconds(),                 //秒 
    "q+" : Math.floor((this.getMonth()+3)/3), //季度 
    "S"  : this.getMilliseconds()             //毫秒 
  }; 
  if(/(y+)/.test(fmt)) 
    fmt=fmt.replace(RegExp.$1, (this.getFullYear()+"").substr(4 - RegExp.$1.length)); 
  for(var k in o) 
    if(new RegExp("("+ k +")").test(fmt)) 
  fmt = fmt.replace(RegExp.$1, (RegExp.$1.length==1) ? (o[k]) : (("00"+ o[k]).substr((""+ o[k]).length))); 
  return fmt; 
}