js 给日期加或者减

减一天------ 2018/3/1--->2018/2/28

let dateTime = new Date("2018-03-01);
dateTime = dateTime.setDate(dateTime.getDate()-1);
dateTime = new Date(dateTime);
console.log(dateTime.toLocaleDatestring());

加一天 ------2018/2/28--->2018/3/1

let dateTime = new Date("2018-02-28");
dateTime = dateTime.setDate(dateTime.getDate()+1);
dateTime = new Date(dateTime);
console.log(dateTime.toLocaleDatestring());