JavaScript Dates and Modern Time with Temporal — Quiz

Review

1. What does a Date object fundamentally store?

   Date stores an ECMAScript time value, represented as a Number, or NaN for an invalid date.
2. What instant is time value 0?

   Zero is the ECMAScript epoch.
3. Which month index represents September in the multi-argument Date constructor?

   Date constructor month arguments are zero-based.
4. What does Date.UTC return?

   Date.UTC computes a time value and returns the Number.
5. Which input is within the standardized ECMAScript date-time string format?

   The ISO-like ECMAScript date-time string format is standardized.
6. What does an explicit +02:00 offset primarily provide when parsing a timestamp?

   The offset identifies the instant represented by the string.
7. Why can getHours() differ from getUTCHours()?

   The same instant can have different local and UTC clock-hour representations.
8. Are Date instances mutable?

   Date setter methods mutate the stored time value.
9. What does getTime() return for an invalid Date?

   Invalid Date has a NaN time value.
10. How is a Date normally serialized by JSON.stringify?

    Date.prototype.toJSON produces an ISO-style UTC string.
11. What does Temporal.Instant model?

    Instant is for an exact point on the time line.
12. Which Temporal type models a calendar date without a time of day?

    PlainDate is date-only.
13. Which Temporal type includes a named time zone?

    ZonedDateTime combines date/time information with a named zone and its rules.
14. What happens when Temporal.PlainDate.add() is called?

    Temporal objects are immutable.
15. What does Temporal.Duration represent?

    Duration is an amount such as days, hours, or minutes.
16. Which modeling choice best matches a birthday?

    A birthday is a calendar date and does not inherently identify an instant.