Dates, time and Intl
Comes up in: JavaScript, UI coding
This concept is being written. It gets the full five steps — explanation, predict, interview angle, practice with tests, and review cards. Here is exactly what it will cover, so you can study it elsewhere in the meantime.
What it covers
Datepitfalls (months 0-based, local vs UTC, parsing)- time zones
Intl.DateTimeFormat,NumberFormat,RelativeTimeFormat,PluralRules,Collator- Temporal status (fact) and polyfill
Words you will know
What you will practise
- format "3 days ago" in en-IN and de-DE
Interview questions this answers
- Why is
new Date("2026-01-01")sometimes a different day in some time zones? - How would you format currency for India vs the US?