javascript 常用获取时间的方法

var now = new Date(); //当前日期 

var nowDayOfWeek = now.getDay(); //本周的第几天 

var nowMonth = now.getMonth(); //当前月 

var nowYear = now.getYear()+1900; //当前年 

var nowY = new Date(nowYear, 0, 1); //今年第一天 

var nowM = new Date(nowYear, nowMonth, 1); //本月第一天 

var nowF = new Date(nowYear-1, 0, 1); //去年第一天 

var nowL = new Date(nowYear-1, 11, 31); //去年最后一天 

var prevDate = new Date(nowYear,nowMonth,0); //上月最后一天 

var pervDateF = new Date(nowYear,nowMonth-1, 1); //上月第一天 

Date.format('yyyy-MM-dd'); //格式化时间;

//封装一个获取时间的方法 

var GetDateStr = function (num) { 

var dd = new Date(); 

dd.setDate(dd.getDate()+num); //获取num天后的日期 

var y = dd.getFullYear(); 

var m = dd.getMonth()+1; //获取当前月份的日期 

var d = dd.getDate(); return y+"-"+m+"-"+d;

 }; 

var weekB = -(nowDayOfWeek-1); 

var weekP = -(nowDayOfWeek+6); 

GetDateStr(weekB); //本周一 

GetDateStr(weekP); //上周一

GetDateStr(weekP+6); //上周末