What she builds
Each tool on DateTimeCalcs starts with a question people search for every day. How long did the shift last? What time will it be in 8 hours? How many business days remain before the deadline? Elizabeth writes the code that answers it and the page that explains the answer.
Most of the work goes into the cases where a quick mental calculation goes wrong:
- a shift that runs past midnight, or through the night the clocks change;
- a federal holiday that falls on a Saturday and is observed on Friday;
- February 29 birthdays, and month-end dates such as January 31 plus one month;
- the exact minute a season starts, which can put the first day of spring on a different date in Honolulu than in New York.
How she checks the results
Rules come from the agencies and laws that set them: NIST for daylight saving time and clock conventions, 5 U.S.C. 6103 and OPM for federal holidays, the Department of Labor and 29 CFR for hours worked and overtime, and NASA data for equinoxes and solstices. Each page lists its sources and the date they were last checked.
Every worked example on the site is also run as an automated test against the calculator code, and an update cannot go live while a test fails. The methodology page lists those rules and test cases.
Corrections
If a result looks wrong, report the error with the page address and the values you entered. Confirmed errors are fixed and the page’s “Updated” date changes with the fix.