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JavaScript Prototype Chain — exercises and bug fixes

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

    Find the prototype

    easy10 min

    Report whether an instance's prototype is the class prototype.

  2. 2

    List the own properties

    easy10 min

    Report the own keys of an instance that also has a method.

  3. 3

    Tell own from inherited

    easy10 min

    Report hasOwnProperty for a property and a method.

  4. 4

    Walk two links up

    easy10 min

    Call a method inherited from the grandparent class.

  5. 5

    Shadow a prototype method

    medium10 min

    Give one instance its own method and leave the other alone.

Find the bug(5)

  1. 1

    Fix the method copied onto the instance

    easy8 min

    A method in the constructor becomes an own property of every instance.

  2. 2

    Fix hasOwnProperty used for a method

    easy8 min

    An inherited method is not an own property.

  3. 3

    Fix the broken chain

    easy8 min

    The middle class does not extend, so the chain stops short.

  4. 4

    Fix the prototype changed for everyone

    easy8 min

    Assigning to the prototype affects every instance, not just one.

  5. 5

    Fix the prototype compared to the class

    easy8 min

    An instance's prototype is the class prototype, not the class.

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