js获取上个月
https://www.cnblogs.com/qiao20/p/9553177.html
new Date() 日期格式处理
https://www.cnblogs.com/zhangxiaoxia/p/9987340.html
function getLastMonthDate(){ var nowdays = new Date(); var year = nowdays.getFullYear(); var month = nowdays.getMonth(); if(month==0){ month = 11; year = year-1; } var mydate=new Date(year,(month+1),0) var startDate = new Date(year,month,1,0,0,0); var endDate = new Date(year,month,mydate.getDate(),23,59,59); return [startDate.getTime(),endDate.getTime(),(month+1)] }