Commonly used date functions in JavaScript

Get the first day of the Week (Monday)

function Getfirstdateofweek (thedate) {
var Firstdateofweek;
Thedate.setdate (thedate.getdate () + 1-thedate.getday ());
Firstdateofweek = thedate;
return firstdateofweek;
}

Get the last day of the Week (Sunday)

function Getlastdateofweek (thedate) {
var Lastdateofweek;
Thedate.setdate (Thedate.getdate () +7-thedate.getday ());
Lastdateofweek = thedate;
return lastdateofweek;
}

Get the first day of last week (Monday)

function Getpreviousfirstdateofweek (thedate) {
var Firstdateofweek;
Thedate.setdate (Thedate.getdate ()-6-thedate.getday ());
Firstdateofweek = thedate;
return firstdateofweek;
}

Get the last day of last week (Sunday)

function Getpreviouslastdateofweek (thedate) {
var Lastdateofweek;
Thedate.setdate (Thedate.getdate ()-thedate.getday ());
Lastdateofweek = thedate;
return lastdateofweek;
}

/---------------------------------------------------
Judging leap years

//---------------------------------------------------
Date.prototype.isleapyear = function ()
{
Return (0==this.getyear ()%4&& (This.getyear ()%100!=0) | | (This.getyear ()%400==0));
}

//---------------------------------------------------
Date formatting
Format Yyyy/yyyy/yy/yy represents year
Mm/m Month
W/W Week
dd/dd/d/d Date
hh/hh/h/h time
mm/m minutes
SS/SS/S/S seconds
//---------------------------------------------------
Date.prototype.format = function (FORMATSTR)
{
var str = FORMATSTR;
var week = [' Day ', ' one ', ' two ', ' three ', ' four ', ' five ', ' six '];

Str=str.replace (/yyyy|yyyy/,this.getfullyear ());
Str=str.replace (/yy|yy/, (this.getyear ()%) >9? ( This.getyear ()%). ToString (): ' 0 ' + (this.getyear ()% 100));

Str=str.replace (/mm/,this.getmonth () >9?this.getmonth (). ToString (): ' 0 ' + this.getmonth ());
Str=str.replace (/m/g,this.getmonth ());

Str=str.replace (/w|w/g,week[this.getday ());

Str=str.replace (/dd|dd/,this.getdate () >9?this.getdate (). ToString (): ' 0 ' + this.getdate ());
Str=str.replace (/d|d/g,this.getdate ());

Str=str.replace (/hh|hh/,this.gethours () >9?this.gethours (). ToString (): ' 0 ' + this.gethours ());
Str=str.replace (/h|h/g,this.gethours ());
Str=str.replace (/mm/,this.getminutes () >9?this.getminutes (). ToString (): ' 0 ' + this.getminutes ());
Str=str.replace (/m/g,this.getminutes ());

Str=str.replace (/ss|ss/,this.getseconds () >9?this.getseconds (). ToString (): ' 0 ' + this.getseconds ());
Str=str.replace (/s|s/g,this.getseconds ());

return str;
}

//+---------------------------------------------------
//| The number of days for two time difference date format is YYYY-MM-DD
//+---------------------------------------------------
function Daysbetween (dateone,datetwo)
{
var onemonth = dateone.substring (5,dateone.lastindexof ('-'));
var oneday = dateone.substring (Dateone.length,dateone.lastindexof ('-') +1);
var oneyear = dateone.substring (0,dateone.indexof ('-'));

var twomonth = datetwo.substring (5,datetwo.lastindexof ('-'));
var twoday = datetwo.substring (Datetwo.length,datetwo.lastindexof ('-') +1);
var twoyear = datetwo.substring (0,datetwo.indexof ('-'));

var cha= (Date.parse (onemonth+ '/' +oneday+ '/' +oneyear ')-date.parse (twomonth+ '/' +twoday+ '/' +twoyear))/86400000);
Return Math.Abs (CHA);
}

//+---------------------------------------------------
//| Date Calculation
//+---------------------------------------------------
Date.prototype.dateadd = function (strinterval, number) {
var dttmp = this;
Switch (strinterval) {
Case ' s ': return new Date (Date.parse (dttmp) + (1000 * number));
Case ' n ': return new Date (Date.parse (dttmp) + (60000 * number));
Case ' H ': return new Date (Date.parse (dttmp) + (3600000 * number));
Case ' d ': return new Date (Date.parse (dttmp) + (86400000 * number));
Case ' W ': Return new Date (Date.parse (dttmp) + ((86400000 * 7) * number));
Case ' Q ': return new Date (Dttmp.getfullyear (), (Dttmp.getmonth ()) + number*3, Dttmp.getdate (), dttmp.gethours (), Dttmp.getminutes (), dttmp.getseconds ());
Case ' m ': return new Date (Dttmp.getfullyear (), (Dttmp.getmonth ()) + number, dttmp.getdate (), dttmp.gethours (), Dttmp.getminutes (), dttmp.getseconds ());
Case ' Y ': return new Date ((Dttmp.getfullyear () + number), Dttmp.getmonth (), Dttmp.getdate (), dttmp.gethours (), Dttmp.getminutes (), dttmp.getseconds ());
}
}

The

//+---------------------------------------------------
//| compares the date difference dtend format to a date type or a valid date format string
//+------------ ---------------------------------------
Date.prototype.datediff = function (Strinterval, dtend) {
var dtstart = This
if (typeof dtend = = ' string ')//if the string is converted to a date type
{
Dtend = stringtodate (dtend);
}
Switch (strinterval) {
case ' s ': Return parseint (Dtend-dtstart)/1000);
Case ' n ': Return parseint ((Dtend-dtstart)/60000);
Case ' h ': Return parseint ((dtend-dtstart)/3600000);
Case ' d ': Return parseint ((dtend-dtstart)/86400000);
Case ' W ': Return parseint (Dtend-dtstart)/(86400000 * 7));
Case ' m ': Return (Dtend.getmonth () +1) + ((Dtend.getfullyear ()-dtstart.getfullyear ()) *12)-(Dtstart.getmonth () +1) ;
Case ' y ': return dtend.getfullyear ()-dtstart.getfullyear ();
}
}

The

//+---------------------------------------------------
//| Date output string that overloads the system's ToString method
//+--------------- ------------------------------------
date.prototype.tostring = function (Showweek)
{
var mydate= this;
var str = mydate.tolocaledatestring ();
if (Showweek)
{
var week = [' Day ', ' one ', ' two ', ' three ', ' four ', ' five ', ' six '];
Str + + ' Week ' + week[mydate.getday ()];
}
return str;
}

//+---------------------------------------------------
//| date Legality validation
//| format: yyyy-mm-dd or YYYY/MM/DD
//+ ---------------------------------------------------
Function Isvaliddate (datestr)
{
var sdate= Datestr.replace (/(^s+|s+$)/g, "); Go to both sides of the space;
if (sdate== ') return true;
//If the format satisfies the yyyy-(/) mm-(/) DD or yyyy-(/) m (/) DD or yyyy-(/) m (/) d or yyyy-(/) mm-(/) d is replaced with the '
//Database tutorial, the legal date can be: yyyy-mm/ DD (2003-3/21), the database is automatically converted to the YYYY-MM-DD format
var s = sdate.replace (/[d]{4,4}[-/]{1}[d]{1,2}[-/]{1}[d]{1,2}/g, ""); if (s== ')//description format satisfies the YYYY-MM-DD or yyyy-m-dd or yyyy-m-d or yyyy-mm-d
{
var t=new date (Sdate.replace (/-/g, '/'));
var ar = sdate.split (/[-/:]/);
if (ar[0]!= t.getyear () | | ar[1]!= t.getmonth () +1 | | ar[2]!= t.getdate ())
{
//alert (' Wrong date format! The format is: Yyyy-mm-dd or YYYY/MM/DD. Notice leap year. ');
return false;
}
}
Else
{
//alert (' Wrong date format! The format is: Yyyy-mm-dd or YYYY/MM/DD. Notice leap year. ');
return false;
}
return true;
}

//+---------------------------------------------------
//| date time check
//| format: yyyy-mm-dd hh:mm:ss
//+---- -----------------------------------------------
Function Checkdatetime (str)
{
var reg =/^ (d+)-(d{1,2})-( D{1,2}) (d{1,2}):(d{1,2}):(d{1,2}) $/;
var r = Str.match (reg);
if (r==null) return false;
R[2]=r[2]-1;
Var d= new Date (r[1],r[2],r[3],r[4],r[5],r[6]);
if (D.getfullyear ()!=r[1]) return false;
if (D.getmonth ()!=r[2]) return false;
if (d.getdate ()!=r[3]) return false;
if (d.gethours ()!=r[4]) return false;
if (d.getminutes ()!=r[5]) return false;
if (D.getseconds ()!=r[6]) return false;
return true;
}

//+---------------------------------------------------
//| to split the date into groups
//+-------------------------------- -------------------
Date.prototype.toarray = function ()
{
var mydate = this;
var myarray = array ();
Myarray[0] = Mydate.getfullyear ();
Myarray[1] = Mydate.getmonth ();
Myarray[2] = Mydate.getdate ();
Myarray[3] = mydate.gethours ();
Myarray[4] = Mydate.getminutes ();
Myarray[5] = Mydate.getseconds ();
return myarray;
}

//+---------------------------------------------------
//| Get Date data information
//| parameter interval representing data type
//| y year m month d days W Week WW Week h when N minute s sec
//+---------------------------------------------------
Date.prototype.datepart = function (int Erval)
{
var mydate = this;
var partstr= ';
var week = [' Day ', ' one ', ' two ', ' three ', ' four ', ' five ', ' six '];
Switch (interval)
{
case ' y ':p artstr = Mydate.getfullyear ();
Case ' m ':p artstr = Mydate.getmonth () +1;break;
Case ' d ':p artstr = Mydate.getdate ();
Case ' W ':p artstr = Week[mydate.getday ()];break;
case ' ww ':p artstr = Mydate.weeknumofyear ();
case ' h ':p artstr = mydate.gethours ();
Case ' n ':p artstr = Mydate.getminutes ();
case ' s ':p artstr = Mydate.getseconds ();
}
Return partstr;
}

//+---------------------------------------------------
//| Gets the maximum number of days of the month in which the current date is located
//+-------------------------- -------------------------
Date.prototype.maxdayofdate = function ()
{
var mydate = this;
var ary = Mydate.toarray ();
var date1 = (new Date (ary[0],ary[1]+1,1));
var date2 = date1.dateadd (1, ' m ', 1);
var result = DateDiff (Date1.format (' Yyyy-mm-dd '), Date2.format (' yyyy-mm-dd '));
return result;
}

//+---------------------------------------------------
//| To get the current date the week is the week ordinal of the year
//+---------------------------------------------------
Date.prototype.weeknumofyear = function ()
{
var mydate = this;
var ary = Mydate.toarray ();
var year = ary[0];
var month = ary[1]+1;
var day = ary[2];
document.write (' < script language=vbscript> n ');
document.write (' mydate = DateValue (' +month+ '-' +day+ '-' +year+ ') n ');
document.write (' result = datepart (' ww ', mydate) n ');
document.write (' n ');
return result;
}

//+---------------------------------------------------
//| string is converted to date type
//| Format mm/dd/yyyy mm-dd-yyyy yyyy/mm/dd yyyy-mm-dd
//+---------------------------------------------------
function Stringtodate (DATESTR)
{

var converted = Date.parse (DATESTR);
var mydate = new Date (converted);
if (isNaN (mydate))
{
//var Delimcahar = datestr.indexof ('/')!=-1? ' /':'-';
var arys= datestr.split ('-');
MyDate = new Date (Arys[0],--arys[1],arys[2]);
}
Return mydate;
}