Check an instance — practice exercise

What you'll be asked to do

1. 1.Check an instanceexercise · easy · 10 min

   Report whether the object was built from the class.

   Passes when: #out should show true.

2. 2.Follow inheritanceexercise · easy · 10 min · practice plan

   Report whether a dog is also an animal.

   Passes when: #out should show true.

3. 3.Show it is not symmetricexercise · easy · 10 min · practice plan

   Report whether an animal is a dog.

   Passes when: #out should show false.

4. 4.Read the exact classexercise · easy · 10 min · practice plan

   Report the exact class name of the instance.

   Passes when: #out should show Dog.

5. 5.Check behaviour insteadexercise · medium · 10 min · practice plan

   Call the method only if the object actually has one.

   Passes when: #out should show woof.

6. 6.Fix typeof used to identify a classbug fix · easy · 8 min

   typeof only ever says object for an instance.

   Passes when: #out should show true.

7. 7.Fix the operands the wrong way roundbug fix · easy · 8 min · practice plan

   The object goes on the left and the class on the right.

   Passes when: #out should show true.

8. 8.Fix the parent checked as a childbug fix · easy · 8 min · practice plan

   A parent instance is not an instance of the child class.

   Passes when: #out should show false.

9. 9.Fix instanceof used for the exact classbug fix · easy · 8 min · practice plan

   instanceof is true for parents too, so it cannot tell the exact class.

   Passes when: #out should show Dog.

10. 10.Fix the class compared as a stringbug fix · easy · 8 min · practice plan

    constructor.name is a string, but the class itself is not.

    Passes when: #out should show Dog.

Between them these tasks cover instanceof, Type checking and constructor.name.

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