js에서 현재 시간대 여름철 발생 및 종료 시간 코드 가져오기

 
  
 
  
 
  
 
  
 
  
 
  <br> 
  <br>function DisplayDstSwitchDates() 
  <br>{ 
  <br>var year = new Date().getYear(); 
  <br>if (year < 1000) 
  <br>year += 1900; 
  <br> 
  <br>var firstSwitch = 0; 
  <br>var secondSwitch = 0; 
  <br>var lastOffset = 99; 
  <br> 
  <br>// Loop through every month of the current year 
  <br>for (i = 0; i < 12; i++) 
  <br>{ 
  <br>// Fetch the timezone value for the month 
  <br>var newDate = new Date(Date.UTC(year, i, 0, 0, 0, 0, 0)); 
  <br>var tz = -1 * newDate.getTimezoneOffset() / 60; 
  <br> 
  <br>// Capture when a timzezone change occurs 
  <br>if (tz > lastOffset) 
  <br>firstSwitch = i-1; 
  <br>else if (tz < lastOffset) 
  <br>secondSwitch = i-1; 
  <br> 
  <br>lastOffset = tz; 
  <br>} 
  <br> 
  <br>// Go figure out date/time occurences a minute before 
  <br>// a DST adjustment occurs 
  <br>var secondDstDate = FindDstSwitchDate(year, secondSwitch); 
  <br>var firstDstDate = FindDstSwitchDate(year, firstSwitch); 
  <br> 
  <br>if (firstDstDate == null && secondDstDate == null) 
  <br>return 'Daylight Savings is not observed in your timezone.'; 
  <br>else 
  <br>return 'Last minute before DST change occurs in ' + 
  <br>year + ': ' + firstDstDate + ' and ' + secondDstDate; 
  <br>} 
  <br> 
  <br>function FindDstSwitchDate(year, month) 
  <br>{ 
  <br>// Set the starting date 
  <br>var baseDate = new Date(Date.UTC(year, month, 0, 0, 0, 0, 0)); 
  <br>var changeDay = 0; 
  <br>var changeMinute = -1; 
  <br>var baseOffset = -1 * baseDate.getTimezoneOffset() / 60; 
  <br>var dstDate; 
  <br> 
  <br>// Loop to find the exact day a timezone adjust occurs 
  <br>for (day = 0; day < 50; day++) 
  <br>{ 
  <br>var tmpDate = new Date(Date.UTC(year, month, day, 0, 0, 0, 0)); 
  <br>var tmpOffset = -1 * tmpDate.getTimezoneOffset() / 60; 
  <br> 
  <br>// Check if the timezone changed from one day to the next 
  <br>if (tmpOffset != baseOffset) 
  <br>{ 
  <br>var minutes = 0; 
  <br>changeDay = day; 
  <br> 
  <br>// Back-up one day and grap the offset 
  <br>tmpDate = new Date(Date.UTC(year, month, day-1, 0, 0, 0, 0)); 
  <br>tmpOffset = -1 * tmpDate.getTimezoneOffset() / 60; 
  <br> 
  <br>// Count the minutes until a timezone chnage occurs 
  <br>while (changeMinute == -1) 
  <br>{ 
  <br>tmpDate = new Date(Date.UTC(year, month, day-1, 0, minutes, 0, 0)); 
  <br>tmpOffset = -1 * tmpDate.getTimezoneOffset() / 60; 
  <br> 
  <br>// Determine the exact minute a timezone change 
  <br>// occurs 
  <br>if (tmpOffset != baseOffset) 
  <br>{ 
  <br>// Back-up a minute to get the date/time just 
  <br>// before a timezone change occurs 
  <br>tmpOffset = new Date(Date.UTC(year, month, 
  <br>day-1, 0, minutes-1, 0, 0)); 
  <br>changeMinute = minutes; 
  <br>break; 
  <br>} 
  <br>else 
  <br>minutes++; 
  <br>} 
  <br> 
  <br>// Add a month (for display) since JavaScript counts 
  <br>// months from 0 to 11 
  <br>dstDate = tmpOffset.getMonth() + 1; 
  <br> 
  <br>// Pad the month as needed 
  <br>if (dstDate < 10) dstDate = "0" + dstDate; 
  <br> 
  <br>// Add the day and year 
  <br>dstDate += '/' + tmpOffset.getDate() + '/' + year + ' '; 
  <br> 
  <br>// Capture the time stamp 
  <br>tmpDate = new Date(Date.UTC(year, month, 
  <br>day-1, 0, minutes-1, 0, 0)); 
  <br>dstDate += tmpDate.toTimeString().split(' ')[0]; 
  <br>return dstDate; 
  <br>} 
  <br>} 
  <br>} 
  <br> 
  <br> 
  
 
  
 
  
 
  <br>document.write("Current date/time: " + new Date() + "<br />"); 
  <br>document.write(DisplayDstSwitchDates()); 
  <br>