一个日期的扩展函数库包括计算周次和本周时间范围(javascript)

/*用相对不规则的字符串来创建日期对象,不规则的含义为:顺序包含年月日三个数值串,有间隔*/
String.prototype.createDate = function(){
var regThree = /^/D*(/d{2,4})/D+(/d{1,2})/D+(/d{1,2})/D*$/;
var regSix = /^/D*(/d{2,4})/D+(/d{1,2})/D+(/d{1,2})/D+(/d{1,2})/D+(/d{1,2})/D+(/d{1,2})/D*$/;
var str = "";
var date = null;
if(regThree.test(this)){
str = this.replace(//s/g,"").replace(regThree,"$1/$2/$3");
date = new Date(str);
}
else if(regSix.test(this)){
str = this.match(regSix);
date = new Date(str[1],str[2]-1,str[3],str[4],str[5],str[6]);
}
if(isNaN(date))return new Date();
else return date;
}

/*
* 功能:根据输入表达式返回日期字符串
* 参数:dateFmt:字符串,由以下结构组成
* yy:长写年,YY:短写年mm:数字月,MM:英文月,dd:日,hh:时,
* mi:分,ss秒,ms:毫秒,we:汉字星期,WE:英文星期.
* isFmtWithZero : 是否用0进行格式化,true or false
*/
Date.prototype.parseString = function(dateFmt,isFmtWithZero){
dateFmt = (dateFmt == null?"yy-mm-dd" : dateFmt);
isFmtWithZero = (isFmtWithZero == null?true : isFmtWithZero);
if(typeof(dateFmt) != "string" )
throw (new Error(-1, 'parseString()方法需要字符串类型参数!'));
var weekArr=[["星期日","星期一","星期二","星期三","星期四","星期五","星期六"],
["SUN","MON","TUR","WED","THU","FRI","SAT"]];
var monthArr=["JAN","FEB","MAR","APR","MAY","JUN","JUL","AUG","SEP","OCT","NOV","DEC"];
var str=dateFmt;
str = str.replace(/yy/g,this.getFullYear());
str = str.replace(/YY/g,this.getYear());
str = str.replace(/mm/g,(this.getMonth()+1).toString().fmtWithZero(isFmtWithZero));
str = str.replace(/MM/g,monthArr[this.getMonth()]);
str = str.replace(/dd/g,this.getDate().toString().fmtWithZero(isFmtWithZero));
str = str.replace(/hh/g,this.getHours().toString().fmtWithZero(isFmtWithZero));
str = str.replace(/mi/g,this.getMinutes().toString().fmtWithZero(isFmtWithZero));
str = str.replace(/ss/g,this.getSeconds().toString().fmtWithZero(isFmtWithZero));
str = str.replace(/ms/g,this.getMilliseconds().toString().fmtWithZeroD(isFmtWithZero));
str = str.replace(/we/g,weekArr[0][this.getDay()]);
str = str.replace(/WE/g,weekArr[1][this.getDay()]);
return str;
}

/*将一位数字格式化成两位,如: 9 to 09*/
String.prototype.fmtWithZero = function(isFmtWithZero){
if(isFmtWithZero)
return (this<10?"0"+this:this);
else return this;
}
String.prototype.fmtWithZeroD = function(isFmtWithZero){
if(isFmtWithZero)
return (this<10?"00"+this:(this<100?"0"+this:this));
else return this;
}

/* 功能 : 返回与某日期相距N天(N个24小时)的日期
* 参数 : num number类型 可以为正负整数或者浮点数,默认为1;
* type 0(秒) or 1(天),默认为秒
* 返回 : 新的PowerDate类型
*/
Date.prototype.dateAfter=function(num,type){
num = (num == null?1:num);
if(typeof(num)!="number") throw new Error(-1,"dateAfterDays(num,type)的num参数为数值类型.");
type = (type==null?0:type);
var arr = [1000,86400000];
var dd = this.valueOf();
dd += num*arr[type];
return new Date(dd);
}

//判断是否是闰年,返回true 或者 false
Date.prototype.isLeapYear = function (){
var year = this.getFullYear();
return (0==year%4 && ((year % 100 != 0)||(year % 400 == 0)));
}

//返回该月天数
Date.prototype.getDaysOfMonth = function (){
return (new Date(this.getFullYear(),this.getMonth()+1,0)).getDate();
}

//转换成大写日期(中文)
Date.prototype.getChinaDate = function(){
var year = this.getFullYear().toString();
var month= this.getMonth()+1;
var day = this.getDate();
var arrNum = ["零","一","二","三","四","五","六","七","八","九","十","十一","十二"];
var strTmp="";
for(var i=0,j=year.length;i<j;i++){
strTmp += arrNum[year.charAt(i)];
}
strTmp += "年";
strTmp += arrNum[month]+"月";
if(day<10)
strTmp += arrNum[day];
else if (day <20)
strTmp += "十"+arrNum[day-10];
else if (day <30 )
strTmp += "二十"+arrNum[day-20];
else
strTmp += "三十"+arrNum[day-30];
strTmp += "日";
return strTmp;
}

//日期比较函数,参数date:为Date类型,如this日期晚于参数:1,相等:0 早于: -1
Date.prototype.dateCompare = function(date){
if(typeof(date) != "object" || !(/Date/.test(date.constructor)))
throw new Error(-1,"dateCompare(date)的date参数为Date类型.");
var d = this.getTime() - date.getTime();
return d>0?1:(d==0?0:-1);
}

/*功能:返回两日期之差
*参数:pd PowerDate对象
* type: 返回类别标识.yy:年,mm:月,ww:周,dd:日,hh:小时,mi:分,ss:秒,ms:毫秒
* intOrFloat :返回整型还是浮点型值 0:整型,不等于0:浮点型
* output : 输出提示,如:时间差为#周!
*/
Date.prototype.calDateDistance = function (date,type,intOrFloat,output){
if(typeof(date) != "object" || !(/Date/.test(date.constructor)))
throw new Error(-1,"calDateDistance(date,type,intOrFloat)的date参数为Date类型.");
type = (type==null?'dd':type);
if(!((new RegExp(type+",","g")).test("yy,mm,ww,dd,hh,mi,ss,ms,")))
throw new Error(-1,"calDateDistance(pd,type,intOrFloat,output)的type参数为非法.");
var iof = (intOrFloat==null?0:intOrFloat);
var miSecMain = this.valueOf();
var miSecSub = date.valueOf();
var num=0;
switch(type){
case "yy": num = this.getFullYear() - date.getFullYear(); break;
case "mm": num = (this.getFullYear() - date.getFullYear())*12+this.getMonth()-date.getMonth(); break;
case "ww": num = ((miSecMain-miSecSub)/7/86400000).fmtRtnVal(iof); break;
case "dd": num = ((miSecMain-miSecSub)/86400000).fmtRtnVal(iof); break;
case "hh": num = ((miSecMain-miSecSub)/3600000).fmtRtnVal(iof); break;
case "mi": num = ((miSecMain-miSecSub)/60000).fmtRtnVal(iof); break;
case "ss": num = ((miSecMain-miSecSub)/1000).fmtRtnVal(iof); break;
case "ms": num = (miSecMain-miSecSub);break;
default: break;
}
if(output)
return output.replace(/#/g," "+num+" ");
else return num;
}

//返回整数或者两位小数的浮点数
Number.prototype.fmtRtnVal = function (intOrFloat){
return (intOrFloat == 0 ? Math.floor(this) : parseInt(this*100)/100);
}

//根据当前日期所在年和周数返回周一的日期
Date.prototype.RtnMonByWeekNum = function (weekNum){
if(typeof(weekNum) != "number")
throw new Error(-1,"RtnByWeekNum(weekNum)的参数是数字类型.");
var date = new Date(this.getFullYear(),0,1);
var week = date.getDay();
week = (week==0?7:week);
return date.dateAfter(weekNum*7-week-7+7,1);
}

//根据当前日期所在年和周数返回周日的日期
Date.prototype.RtnSunByWeekNum = function (weekNum){
if(typeof(weekNum) != "number")
throw new Error(-1,"RtnByWeekNum(weekNum)的参数是数字类型.");
var date = new Date(this.getFullYear(),0,1);
var week = date.getDay();
week = (week==0?7:week);
return date.dateAfter(weekNum*7-week-2+7,1);
}

//通过当前时间计算当前周数
Date.prototype.getWeekNumber = function() {
 var d = new Date(this.getFullYear(), this.getMonth(), this.getDate(), 0, 0, 0);
 var DoW = d.getDay();
 d.setDate(d.getDate() - (DoW + 6) % 7 + 3); // Nearest Thu
 var ms = d.valueOf(); // GMT
 d.setMonth(0);
 d.setDate(4); // Thu in Week 1
 return Math.round((ms - d.valueOf()) / (7 * 864e5)) + 1;
}

//得到今天的年,月,日
function getMyToday()
{
    this.now = new Date();
    this.year = this.now.getFullYear();
    this.month = this.now.getMonth();
    this.day = this.now.getDate();
}

//显示生成的时间范围
function weekSelectInitial(){
    var date = new Date();
    var weeknum = date.getWeekNumber();
    var thisyear; //真正的今年年份   
    thisyear=new getMyToday();
    thisyear=thisyear.year;
    weekstring = date.RtnMonByWeekNum(weeknum).parseString("yy-mm-dd")+"到"+date.RtnSunByWeekNum(weeknum).parseString("yy-mm-dd");
    document.all.item_edt_addWeek.value=weekstring;
}

//显示生成的周次
function weekSelectNumInitial(){
 var thisyear; //真正的今年年份   
     thisyear=new getMyToday();
     thisyear=thisyear.year;
 var date = new Date();
 var weeknum = date.getWeekNumber() + 1;
 document.all.item_edt_weekNum.value=thisyear+"年第"+weeknum+"周";
}