I have tested the Seconds Calculators under 5 different browsers:
Mozilla Firefox
Konqueror
Netscape
Opera
Microsoft Internet Explorer
All but Internet Explorer seem to comply with current javascript (ECMAScript) standards, and perform all operations successfully. I therefore have reason to believe that other compliant browsers will also run these scripts with no problem. If you encounter an anomaly, please let me know your browser when / if you report the problem to me.
As a firm believer in open web design, I strive to achieve browser-independent functionality. I have gone to some trouble to work around the dysfunctional quirks of Internet Explorer (IE), but remain uncertain and uneasy about it. So, rather than risk inaccurate calculations, I have added another layer of diagnostics, and have disabled the calculations under IE and other non-compliant javascript interpreters. If you have access to any other browser, please use it rather than IE. You might even consider upgrading to Linux, so as to avoid Microsoft anomalies and limitations altogether. :-)
The minimum javascript version for these scripts appears to be 1.4 or 1.5. I have run the calculations successfully under 1.5 and 1.6. Version 1.4 might work OK, but 1.3 or older would be doubtful. My current guess is that any browser (except IE) released around 2003 or later should be fine. This guess is based upon the fact that javascript 1.5 standards were released in late 2000, with 1.6 released in 2005. Some oddball browsers may be newer than this and still fail my internal diagnostics. If you think your browser is OK, but is failing my tests, please let me hear from you, as noted in the "End notes".
As of my Seconds Calculators release 1.1.000, the automatic daylight / standard timezone adjustment in the post-submit calculations 3, 4, 5, and 6 no longer depends upon your browser's built-in logic for daylight / standard times for American timezones. So daylight / standard logic should work OK in browsers released before the new (2007) daylight saving rules. For more on time zones and rules governing daylight / standard times, see the timezone notes page.