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JavaScript Reflect — exercises and bug fixes

5 hands-on exercises and 5 find-the-bug challenges for the JavaScript Reflect 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

    Read with Reflect.get

    easy10 min

    Read a property using Reflect instead of dot notation.

  2. 2

    Check with Reflect.has

    easy10 min

    Check a property exists using Reflect.

  3. 3

    Forward a read inside a Proxy

    easy10 min

    Use Reflect.get inside a get trap.

  4. 4

    Check whether a write succeeded

    easy10 min

    Report whether writing to a frozen object worked.

  5. 5

    List own keys

    medium10 min

    List an object's own property names with Reflect.

Find the bug(5)

  1. 1

    Fix Reflect.get given the arguments in the wrong order

    easy8 min

    The target comes first and the key second.

  2. 2

    Fix the trap that does not forward to Reflect

    easy8 min

    Returning a hardcoded value ignores whatever the target actually holds.

  3. 3

    Fix Reflect.set checked with the wrong result

    easy8 min

    A successful write returns true, a refused one returns false.

  4. 4

    Fix Object.keys used where symbols matter

    easy8 min

    Reflect.ownKeys includes symbol keys that Object.keys skips.

  5. 5

    Fix deleteProperty never called

    easy8 min

    The property is still there because nothing actually removed it.

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