Functions and methods for processing dates in Javascript

1. Solve 2000 problems
Function Y2K (number) {return (number <1000 )? Number + 1900: Number ;}
2. Check whether the date is valid
// When the input parameter is isdate (DD, mm, ccyy), it indicates the year, month, and day to be checked.
// When the input parameter is isdate (DD, mm), the default year is the current year.
// When the input parameter is isdate (dd), it indicates the default year, and the month indicates the current year.
// Ensure that the input month is less than 1-12.

Function isdate (day, month, year ){
VaR today = new date ();
Year = ((! Year )? Y2K (today. getyear () year );
Month = ((! Month )? Today. getmonth (): month-1 );
If (! Day) return false
VaR test = new date (year, month, day );

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If (Y2K (test. getyear () = year )&&
(Month = test. getmonth ())&&
(Day = test. getdate ()))
Return true;
Else
Return false
}

The following is a call example:
If (isdate (1997 ))
Document. Write ("valid ");
Else
Document. Write ("invalid ");

3. How to determine the number of days between two dates
Function dayselapsed (date1, date2 ){
VaR Difference = date. UTC (date1.getyear (), date1.getmonth (), date1.getdate (), 0, 0)
-Date. UTC (date2.getyear (), date2.getmonth (), date2.getdate (), 0, 0 );
Return Difference/1000/60/60/24;

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}

4. How to pass the month in a drop-down list box to another page
<Form>
<Select name = "selectname">
<Option> January
<Option> February
<Option> March
<Option> CMDL
<Option> May
<Option> June
<Option> July
<Option> August
<Option> spetember
<Option> October
<Option> November
<Option> December
</SELECT>
<Input type = "button" value = "go" onclick = "window. Location. href = 'nextpage.html? '+
This. Form. selectname. Options [This. Form. selectname. selectedindex]. Text ">
</Form>

Add the followingCode
<Form name = "formname"> <input type = "text" name = "textname"> <form>
<Script language = "JavaScript"> <
Document. formname. textname. value = location. Search. substring (1 );
//-Script>

Or:
<Script language = "JavaScript"> <www.86oo.com
Document. Write ("<form> <input type = 'text '");
Document. Write ("value = '" location. Search. substring (1) + "form> ")
//-Script>

5. How to compare the time in a string with the current time
<Script language = "JavaScript">
/* The date string can be in the following format:
Format: 19970529
Format: 970529
Format 3: 29/05/1997
Format 4: 29/05/97
The input parameter datetype is a number ranging from 1 to 4, indicating the format used.
*/
<! -
Function isittoday (datestring, datetype ){
VaR now = new date ();
VaR today = new date (now. getyear (), now. getmonth (), now. getdate ())

If (datetype = 1)
VaR date = new date (datestring. substring (0, 4 ),
Datestring. substring (4, 6)-1,

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Datestring. substring (6, 8 ));
Else if (datetype = 2)
VaR date = new date (datestring. substring (0, 2 ),
Datestring. substring (2, 4)-1,
Datestring. substring (4, 6 ));
Else if (datetype = 3)
VaR date = new date (datestring. substring (6, 10 ),
Datestring. substring (3,5)-1,

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datestring. substring (0, 2);
else if (datetype = 4)
var date = new date (datestring. substring (6, 8),
datestring. substring (3, 5)-1,
datestring. substring (0, 2);
else
return false;

If (date. tostring () = today. tostring ()
return true;
else
return false; the Article from 86oo.com
}< br> is called as follows:
If (isittoday ("19970529", 1) Alert ('true'); else alert ('false');
If (isittoday ("970529 ", 2) Alert ('true'); else alert ('false');
If (isittoday ("29/05/1997", 3) Alert ('true '); else alert ('false');
If (isittoday ("02/06/97", 4) Alert ('true'); else alert ('false ');
//-

6. How to calculate the age based on a person's birthday
<Script language = "JavaScript"> <
/* The date string can be in the following format:
Format: 19970529
Format: 970529
Format 3: 29/05/1997
Format 4: 29/05/97
The input parameter datetype is a number ranging from 1 to 4, indicating the format used.
*/
Function getage (datestring, datetype ){
VaR now = new date ();
VaR today = new date (now. getyear (), now. getmonth (), now. getdate ())
VaR yearnow = now. getyear ();
VaR monthnow = now. getmonth ();

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VaR datenow = now. getdate ();

If (datetype = 1)
VaR DOB = new date (datestring. substring (0, 4 ),
Datestring. substring (4, 6)-1,
Datestring. substring (6, 8 ));
Else if (datetype = 2)
VaR DOB = new date (datestring. substring (0, 2 ),
Datestring. substring (2, 4)-1,
Datestring. substring (4, 6 ));

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Else if (datetype = 3)
VaR DOB = new date (datestring. substring (6, 10 ),
Datestring. substring (3,5)-1,
Datestring. substring (0, 2 ));
Else if (datetype = 4)
VaR DOB = new date (datestring. substring (6, 8 ),
Datestring. substring (3,5)-1,
Datestring. substring (0, 2 )); 86oo tutorial
Else
Return '';

VaR yeardob = Dob. getyear ();
VaR monthdob = Dob. getmonth ();
VaR datedob = Dob. getdate ();

Yearage = yearnow-yeardob;

If (monthnow> monthdob)
VaR monthage = monthnow-monthdob;
Else {
Yearage --;
VaR monthage = 12 + monthnow-monthdob;
}
If (datenow> datedob)
VaR dateage = datenow-datedob;
Else {
Monthage --;
VaR dateage = 31 + datenow-datedob;

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}

Return yearage + 'ears' + monthage + 'months' + dateage + 'days ';
}
Call example
Document. Write (getage ("19650104", 1) + 'br> ')
Document. Write (getage ("650104", 2) + 'br> ')
Document. Write (getage ("04/01/1965", 3) + 'br> ')
Document. Write (getage ("04/01/65", 4) + 'br> ')
//-Script>

7. How to use the following format dd/mm/yy to display the date on the webpage
<Script language = 'javascript '>
<! -
VaR date = new date ();
VaR d = date. getdate ();
VaR day = (d <10 )? '0' + D: D;
VaR M = date. getmonth () + 1;
VaR month = (M <10 )? '0' + M: m;
VaR YY = date. getyear ();
VaR year = (yy <1000 )? YY + 1900: yy;

Document. Write (day + "/" + month + "/" + year );
//-
</SCRIPT>

8. How to use the following format date month year to display a date on a webpage
<Script language = 'javascript '>86oo.com provides various tutorials
<! -
Function makearray (){
For (I = 0; I <makearray. Arguments. length; I ++)
This [I + 1] = makearray. Arguments [I];
}

VaR months = new makearray ('january ', 'february', 'march ',
'0000l', 'may', 'june', 'july', 'August ', 'September ',
'October ', 'november', 'december ');

VaR date = new date ();
VaR day = date. getdate ();
VaR month = date. getmonth () + 1;
VaR YY = date. getyear ();
VaR year = (yy <1000 )? YY + 1900: yy;

Document. Write (day + "" + months [month] + "" + year );
//-
</SCRIPT>

9. How to make the last update date of my webpage easier to read
<Script language = 'javascript '> <
Function makearray0 (){
For (I = 0; I <makearray0.arguments. length; I ++)
This [I] = makearray0.arguments [I];

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}< br> var days = new makearray0 ("Sunday", "Monday", "Tuesday", "Wednesday",
"Thursday", "Friday ", "Saturday");
var months = new makearray0 ('january', 'february ', 'march',
'marril', 'may ', 'june', 'july', 'August ', 'September',
'October ', 'November', 'december ');
function nths (day) {
If (Day = 1 | day = 21 | day = 31)
return 'st ';
else
If (Day = 2 | day = 22)
return 'nd ';
If (Day = 3 | day = 23)
return 'rd';

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Else return 'th ';
}
Function Y2K (number) {return (number <1000 )? Number + 1900: Number ;}
VaR last = Document. lastmodified;
VaR date = new date (last );
Document. Write ("Last updated on" + days [date. getday ()] + ''+
Date. getdate () + nths (date. getdate () + "" +
Months [date. getmonth ()] + "," +
(Y2K (date. getyear () + "."
//-Script>

10. How to display the countdown to a specific date
<Script language = "JavaScript"> <
Function Y2K (number) {return (number <1000 )? Number + 1900: Number ;}

Function timetilldate (whenday, whenmonth, whenyear ){
VaR now = new date ();
VaR ThisDay = now. getdate (), thismonth = now. getmonth () + 1, Thisyear = Y2K (now. getyear ())
VaR yearsdifference = whenyear-Thisyear, monthsdifference = 0, daysdifference = 0, string = '';

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If (whenmonth> = thismonth) monthsdifference = whenmonth-thismonth;
Else {yearsdifference --; monthsdifference = whenmonth + 12-thismonth ;}

If (whenday> = ThisDay) daysdifference = whenday-ThisDay;
Else {
If (monthsdifference> 0) monthsdifference --;
Else {yearsdifference --; monthsdifference + = 11 ;}
Daysdifference = whenday + 31-ThisDay;
}

If (yearsdifference <0) return '';

If (yearsdifference = 0) & (monthsdifference = 0) & (daysdifference = 0 ))
Return '';

If (yearsdifference> 0) {
string = yearsdifference + 'Year'; 86oo.com provides various tutorials
If (yearsdifference> 1) string + = 's';
string + = '';
}

If (monthsdifference> 0 ){
String + = monthsdifference + 'month ';
If (monthsdifference> 1) string + ='s ';
String + = '';
}
If (daysdifference> 0 ){
String + = daysdifference + 'day ';
If (daysdifference> 1) string + ='s ';
String + = '';
}

VaR Difference = date. UTC (now. getyear (), now. getmonth (), now. getdate (), now. gethours (), now. getminutes (), now. getseconds ())-

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Date. UTC (now. getyear (), now. getmonth (), now. getdate (), 0, 0 );

Difference = 1000*60*60*24-difference;

VaR hoursdifference = math. Floor (difference/1000/60/60 );
Difference = difference-hoursdifference x 1000*60*60
VaR minutesdifference = math. Floor (difference/1000/60 );
Difference = difference-minutesdifference * 1000*60
VaR secondsdifference = math. Floor (difference/1000 );

If (hoursdifference> 0 ){
String + = hoursdifference + 'hour ';
If (hoursdifference> 1) string + ='s ';
String + = '';
}

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If (minutesdifference> 0 ){
String + = minutesdifference + 'minute ';
If (minutesdifference> 1) string + ='s ';
String + = '';
}

If (secondsdifference> 0 ){
String + = secondsdifference + 'second ';
If (secondsdifference> 1) string + ='s ';
String + = '';
}
Return string;
}

Call example, for example, how long is there till now at 31/12/1999.
Document. Write (timetilldate (1999 ));
//-Script>

11. How to remove hours from a date
<Script language = 'javascript '> <
VaR date = new date ();
VaR date = new date (date. UTC (date. getyear (), date. getmonth (), date. getdate (), date. gethours (), date. getminutes (), date. getseconds ()-5x60x60*1000 );

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Document. Write (date );
//-Script>

12. How to add a few months in a date and display it correctly
<Script language = "JavaScript"> <
Function makearray (){
For (I = 0; I <makearray. Arguments. length; I ++)
This [I + 1] = makearray. Arguments [I];
}
VaR months = new makearray ('january ', 'february', 'march', 'mongol ',
'May', 'june', 'july', 'August ', 'September ',
'October ', 'november', 'december ');
Function nths (day ){
If (Day = 1 | day = 21 | day = 31) return 'st ';
Else if (Day = 2 | day = 22) return 'nd'; 86oo.com
Else if (Day = 3 | day = 23) return 'rd ';
Else return 'th ';
}
Function Y2K (number) {return (number <1000 )? Number + 1900: Number ;}
Function monthsahead (noofmonths ){
VaR today = new date ();
VaR date = new date (today. getyear (), today. getmonth () + noofmonths, today. getdate (), today. gethours (), today. getminutes (), today. getseconds ())
Return date. getdate () + nths (date. getdate () + ''+ months [date. getmonth () + 1] + ''+ Y2K (date. getyear ())
}

Call example:
Document. Write (monthsahead (6 ));
//-Script>