js获取指定间隔天数的起止日期

// 当需要查询前n天的记录时,获取起止日期并查数据(日期格式为八位字符串)function getDate(dateLength){var now = new Date();var year = now.getFullYear();var month =(now.getMonth() + 1).toString();var day = (now.getDate()-1).toString();if (month.length == 1) {month = "0" + month;}if (day.length == 1) {day = "0" + day;}EndDate = year + month +  day;now.setDate(now.getDate()-dateLength);//获取dateLength天前的日期 ;var year = now.getFullYear();var month =(now.getMonth() + 1).toString();var day = (now.getDate()).toString();if (month.length == 1) {month = "0" + month;}if (day.length == 1) {day = "0" + day;}BeginDate = year + month +  day;//在此处可以调用加载数据的方法        //loadData(BeginDate,EndDate);}

//调用(当前日期为20180531)getDate(7);//BeginDate:20180524  EndDate:20180530