//昨天的时间
 var day1 = new Date();
 day1.setTime(day1.getTime()-24*60*60*1000);
 var s1 = day1.getFullYear()+"-" + (day1.getMonth()+1) + "-" + day1.getDate();
 //今天的时间
 var day2 = new Date();
 day2.setTime(day2.getTime());
 var s2 = day2.getFullYear()+"-" + (day2.getMonth()+1) + "-" + day2.getDate();
 //明天的时间
 var day3 = new Date();
 day3.setTime(day3.getTime()+24*60*60*1000);
 var s3 = day3.getFullYear()+"-" + (day3.getMonth()+1) + "-" + day3.getDate();
 //拼接时间
 function show(){
  var str = "" + s1 + "至" + s2;
  return str;
 }