var d1 = new Date(2009, 0, 1);
var d2 = new Date(2009, 6, 1);
if (d1.getTimezoneOffset() != d2.getTimezoneOffset())
{
alert(‘Daylight Saving Time‘); //夏令时
}
else
{
alert(‘Daylight Time‘); //非夏令时
}原文：http://blog.csdn.net/jcx5083761/article/details/19649821