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Js obtains the time code of occurrence and termination in the current time zone.
This article mainly introduces the time code for js to obtain the occurrence and termination of the token in the current time zone. For more information, see
The Code is as follows:
<! DOCTYPE html>
<Html>
<Head>
<Title> DST Calculator </title>
<Script type = "text/javascript">
Function DisplayDstSwitchDates ()
{
Var year = new Date (). getYear ();
If (year <1, 1000)
Year + = 1900;
Var firstSwitch = 0;
Var secondSwitch = 0;
Var lastOffset = 99;
// Loop through every month of the current year
For (I = 0; I <12; I ++)
{
// Fetch the timezone value for the month
Var newDate = new Date (Date. UTC (year, I, 0, 0, 0, 0, 0 ));
Var tz =-1 * newDate. getTimezoneOffset ()/60;
// Capture when a timzezone change occurs
If (tz> lastOffset)
FirstSwitch = I-1;
Else if (tz <lastOffset)
SecondSwitch = I-1;
LastOffset = tz;
}
// Go figure out date/time occurences a minute before
// A DST adjustment occurs
Var secondDstDate = FindDstSwitchDate (year, secondSwitch );
Var firstDstDate = FindDstSwitchDate (year, firstSwitch );
If (firstDstDate = null & secondDstDate = null)
Return 'daylight Savings is not observed in your timezone .';
Else
Return 'last minute before DST change occurs in '+
Year + ':' + firstDstDate + 'and' + secondDstDate;
}
Function FindDstSwitchDate (year, month)
{
// Set the starting date
Var baseDate = new Date (Date. UTC (year, month, 0, 0, 0, 0, 0 ));
Var changeDay = 0;
Var changeMinute =-1;
Var baseOffset =-1 * baseDate. getTimezoneOffset ()/60;
Var dstDate;
// Loop to find the exact day a timezone adjust occurs
For (day = 0; day <50; day ++)
{
Var tmpDate = new Date (Date. UTC (year, month, day, 0, 0, 0, 0 ));
Var tmpOffset =-1 * tmpDate. getTimezoneOffset ()/60;
// Check if the timezone changed from one day to the next
If (tmpOffset! = BaseOffset)
{
Var minutes = 0;
ChangeDay = day;
// Back-up one day and grap the offset
TmpDate = new Date (Date. UTC (year, month, day-1, 0, 0, 0, 0 ));
TmpOffset =-1 * tmpDate. getTimezoneOffset ()/60;
// Count the minutes until a timezone chnage occurs
While (changeMinute =-1)
{
TmpDate = new Date (Date. UTC (year, month, day-1, 0, minutes, 0, 0 ));
TmpOffset =-1 * tmpDate. getTimezoneOffset ()/60;
// Determine the exact minute a timezone change
// Occurs
If (tmpOffset! = BaseOffset)
{
// Back-up a minute to get the date/time just
// Before a timezone change occurs
TmpOffset = new Date (Date. UTC (year, month,
Day-1, 0, minutes-1, 0, 0 ));
ChangeMinute = minutes;
Break;
}
Else
Minutes ++;
}
// Add a month (for display) since JavaScript counts
// Months from 0 to 11
DstDate = tmpOffset. getMonth () + 1;
// Pad the month as needed
If (dstDate <10) dstDate = "0" + dstDate;
// Add the day and year
DstDate + = '/' + tmpOffset. getDate () + '/' + year + '';
// Capture the time stamp
TmpDate = new Date (Date. UTC (year, month,
Day-1, 0, minutes-1, 0, 0 ));
DstDate + = tmpDate. toTimeString (). split ('') [0];
Return dstDate;
}
}
}
</Script>
</Head>
<Body>
<Script type = "text/javascript">
Document. write ("Current date/time:" + new Date () + "<br/> ");
Document. write (DisplayDstSwitchDates ());
</Script>
</Body>
</Html>
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