George V. Reilly

Daylight Saving Time

Daylight Saving Time is hot garbage is a typical article you can expect to read this weekend condemning DST.

My own dislike of DST was boosted when I worked on calendar software at Cozi. We learned the hard way that we needed to test our latest software ahead of both the start and end of DST each year. That's trickier than you might think. Setting the computer's clock forward a couple of weeks, past the change of DST, is one thing; getting the changed time to last for more than a few minutes is another. Most computers ag­gres­sive­ly sync their clocks to a network time server, which can be tricky to continue.

Odds and Ends #12

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Daylight Savings Time and JavaScript

The JavaScript engines in Firefox 2 (Windows) and IE6 can't handle the new Daylight Savings Time rules in the U.S. The Date() function returns a value that is off by an hour if the system time is between the second Sunday of March and the first Sunday of April.

More at the Cozi Tech Blog.

Update 2008/03/14: Mea culpa. This is not a widespread problem. It is caused by the presence of set TZ=PST8PDT in my C:\AutoExec.bat. Per KB932590, the existence of the TZ en­vi­ron­ment variable will cause the CRT to use the old DST rules. (I can't remember why I set TZ several years ago. It's part of the ac­cu­mu­lat­ed mess of continue.