Js Date对象 简单操作

//JavaScript Document
var finalMonth =['Jan','Feb','Mar','Apr','May','Jun','Jul','Aug','Sep','Oct','Nov','Dec'];
var finalWeek = ['Mon','Tues','Wed','Thur','Fri','Sat','Sun'];

// date : Mon May 11 13:53:08 UTC+0800 2015
/**
*	param  Date对象：Mon May 11 13:53:08 UTC+0800 2015
*	return yyyy-MM-dd
*/
function getTodayFormatea(param){
var result = "";
if(param==null){
param = new Date();
}
var dateStr = param.toString();
var dateArr = dateStr.split(" ");
var dateMonth= getMonthNum(dateArr[1]);
var dateDay = dateArr[2];
var dateYear = dateArr[5];
if(dateDay<10){
dateDay="0"+dateDay;
}
if(dateMonth<10){
dateMonth="0"+dateMonth;
}
result = ""+dateYear+"-"+dateMonth+"-"+dateDay;
return result;
}
/**
*	param  Date对象：Mon May 11 13:53:08 UTC+0800 2015
*	return yyyy/MM/dd
*/
function getTodayFormate(param){
var result = "";
if(param==null){
param = new Date();
}
var dateStr = param.toString();
var dateArr = dateStr.split(" ");
var dateMonth= getMonthNum(dateArr[1]);
var dateDay = dateArr[2];
var dateYear = dateArr[5];
if(dateDay<10){
dateDay="0"+dateDay;
}
if(dateMonth<10){
dateMonth="0"+dateMonth;
}
result = ""+dateYear+"/"+dateMonth+"/"+dateDay;
return result;
}
/**
*	param  Date Object：Mon May 11 13:53:08 UTC+0800 2015
*	n 自param 起向后多少天
*	return Date Object：Mon May 11 13:53:08 UTC+0800 2015
*/
function getDateBeforeParamDate(param,n){
var result = new Date();
if(param==null){
param = result;
}
if(n==null){
n=0;
}
param = new Date(param);
millSecond = param.valueOf();
millSecond =  millSecond - n*24*3600*1000;
result = new Date(millSecond);
result = getTodayFormatea(result);
return result;
}
/**
*	param  Date对象：Mon May 11 13:53:08 UTC+0800 2015
*	n 自param 向前多少天
*	return Date Object：Mon May 11 13:53:08 UTC+0800 2015
*/
function getDateNextParamDate(param,n){
var result = new Date();
if(param==null){
param = result;
}
if(n==null){
n=0;
}
param = new Date(param);
millSecond = param.valueOf();
millSecond = millSecond + n*24*3600*1000;
result = new Date(millSecond);
result = getTodayFormatea(result);
return result;
}
/**
*	根据月份简称获取获取对应的数值
*
*/
function getMonthNum(param){
var result = 0;
for(var i=1;i<13;i++){
if(param==finalMonth[i-1]){
result=i;
}
}
return result;
}
/**
*	根据星期简称获取对应的数值
*
*/
function getWeekNum(param){
var result = 0;
for(var i=1;i<8;i++){
if(param == finalWeek[i-1]){
result =i;
}
}
return result;
}