js获取当前时间，往前或往后推多少天并且判断是星期几

var now = new Date();
var date = new Date(now.getTime() +1 * 24 * 3600 * 1000);
var year = date.getFullYear();
var month = date.getMonth() + 1;
var day = date.getDate();
var hour = date.getHours();
var minute = date.getMinutes();
var second = date.getSeconds();
alert(year + ‘-’ + month + ‘-’ + day + ’ ’ + hour + ‘:’ + minute + ‘:’ + second);
var year = year, month = month, date = day;
var dt = new Date(year, month, date), dt2 = new Date(now.getTime() -4 * 24 * 3600 * 1000);
var weekDay = [“周天”, “周一”, “周二”, “周三”, “周四”, “周五”, “周六”];
alert(weekDay[dt2.getDay()]);
有需要的可以复制代码去看看弹出来的结果，箭头的位置都是可以改的，往后推算时间的话就是加，往前推算是减