In "19" + date.getYear() - 10, JavaScript was adopted for the web and devs broke time itself. Daylight saving time was ignored, and calendars started the week on the wrong day. This caused chaos. Meetings were missed. Every March, the clocks sprang forward and the pill reminders didn't. Nine months later, I was born.
This lead to endless workarounds to get those times fixed. Developers formatted every date on the server and kept hand-written tables of which countries start the week on Sunday. Then Moment.js arrived in 2011, and moment-timezone shipped the entire world's time zone database to your users' browsers just to tell them what time it was. The Intl API landed in 2012. Then a spec change made dates show up a day early, so developers added "T00:00" to every date string. Durations got no fix at all, so "1h 20m" was built by hand, in every language.
Today, the fixes are finally built in. Temporal, Intl.Locale, and Intl.DurationFormat replace every one of those workarounds, and this talk shows you how to apply them.