Whetstone

Dates & Time

The date bugs that reach production, and how to avoid them: a Date is one instant read through the machine's time zone, so store UTC and render in the viewer's zone; parse only ISO strings and format with Intl; keep birthdays and due dates as date-only values with their own arithmetic, because DST days aren't 24 hours; then when a library is worth it, and where Temporal stands.

  1. 1. The Date object: one number, many getters

    Lesson · Intro · ~20 min
    • JavaScript
    • Dates & Time

  2. 2. UTC vs local time

    Lesson · Core · ~30 min
    • JavaScript
    • Dates & Time
    • Time Zones

  3. 3. Parsing & formatting dates

    Lesson · Core · ~30 min
    • JavaScript
    • Dates & Time
    • Intl
    • Time Zones

  4. 4. Date-only values & daylight saving time

    Full · Advanced · ~45 min
    • JavaScript
    • Dates & Time
    • Time Zones
    • Date Arithmetic

  5. 5. Date libraries: when, which, and where Temporal stands

    Card · Core · ~10 min
    • JavaScript
    • Dates & Time
    • Time Zones
    • Date Libraries