Build a date — practice exercise

What you'll be asked to do

1. 1.Build a dateexercise · easy · 10 min

   Create January 15 2026 and report the year.

   Passes when: #out should show 2026.

2. 2.Read the month numberexercise · easy · 10 min · practice plan

   Report the month number for January.

   Passes when: #out should show 0.

3. 3.Read the day of the monthexercise · easy · 10 min · practice plan

   Report the day of the month.

   Passes when: #out should show 15.

4. 4.Parse an ISO stringexercise · easy · 10 min · practice plan

   Parse a date string and report the year.

   Passes when: #out should show 2026.

5. 5.Copy before changingexercise · medium · 10 min · practice plan

   Change a copy and report the original day.

   Passes when: #out should show 15.

6. 6.Fix the month passed as a real numberbug fix · easy · 8 min

   Months start at zero, so January is 0.

   Passes when: #out should show January.

7. 7.Fix getDay used for the datebug fix · easy · 8 min · practice plan

   getDay gives the weekday, not the day of the month.

   Passes when: #out should show 15.

8. 8.Fix the original changedbug fix · easy · 8 min · practice plan

   Setters modify the date in place, so copy first.

   Passes when: #out should show 15.

9. 9.Fix getYear usedbug fix · easy · 8 min · practice plan

   getYear is an old method; getFullYear is the correct one.

   Passes when: #out should show 2026.

10. 10.Fix the date built from a loose stringbug fix · easy · 8 min · practice plan

    Only the ISO format parses consistently.

    Passes when: #out should show 2026.

Between them these tasks cover Date, Month numbering and Timestamps.

Looking for a different chapter? See every practice set, or switch to the interview theory questions.