JS日期格式化，拿到时间段日期

//日期操作（yyyy-mm-dd,30,+/-）

function dateOperator(date,days,operator){

date = date.replace(/-/g,"/");
var nd = new Date(date);
nd = nd.valueOf();
if(operator=="+"){
nd = nd + days * 24 * 60 * 60 * 1000;
}else if(operator=="-"){
   nd = nd - days * 24 * 60 * 60 * 1000;
}else{
   return false;
}
nd = new Date(nd);
var y = nd.getFullYear();
var m = nd.getMonth()+1;
var d = nd.getDate();
if(m <= 9) m = "0"+m;
if(d <= 9) d = "0"+d; 
var temdate = y+"-"+m+"-"+d;
return temdate ;
}

//日期格式化

function dateToString(sdate){
if(sdate instanceof Date){ 
var dd = sdate.getDate() < 10 ? "0" + sdate.getDate() : sdate.getDate().toString();  
var mmm = (sdate.getMonth()+1) < 10? "0"+(sdate.getMonth()+1) : (sdate.getMonth()+1);  
var yyyy = sdate.getFullYear().toString();  
return yyyy+'-'+mmm+'-'+dd;  
}else{
return sdate;
}

}

例如要拿到当前日期减30天的时间：var startDate = dateOperator(dateToString(new Date()),30,"-");
     当前时间：var endDate = dateToString(new Date());