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JavaScript Dates — exercises and bug fixes

5 hands-on exercises and 5 find-the-bug challenges for the JavaScript Dates lesson. Every one is checked automatically in the browser — write the code, run it, and the tests tell you what still fails.

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Exercises(5)

  1. 1

    Build a date

    easy10 min

    Create January 15 2026 and report the year.

  2. 2

    Read the month number

    easy10 min

    Report the month number for January.

  3. 3

    Read the day of the month

    easy10 min

    Report the day of the month.

  4. 4

    Parse an ISO string

    easy10 min

    Parse a date string and report the year.

  5. 5

    Copy before changing

    medium10 min

    Change a copy and report the original day.

Find the bug(5)

  1. 1

    Fix the month passed as a real number

    easy8 min

    Months start at zero, so January is 0.

  2. 2

    Fix getDay used for the date

    easy8 min

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

  3. 3

    Fix the original changed

    easy8 min

    Setters modify the date in place, so copy first.

  4. 4

    Fix getYear used

    easy8 min

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

  5. 5

    Fix the date built from a loose string

    easy8 min

    Only the ISO format parses consistently.

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