Copy a primitive — practice exercise

What you'll be asked to do

1. 1.Copy a primitiveexercise · easy · 10 min

   Copy a number, change the copy, and report the original.

   Passes when: #out should show 1.

2. 2.Share an objectexercise · easy · 10 min · practice plan

   Assign an object to a second name, change it, and report the first.

   Passes when: #out should show 2.

3. 3.Copy an object properlyexercise · easy · 10 min · practice plan

   Spread the object so the original is left alone.

   Passes when: #out should show 1 and 2.

4. 4.Copy an arrayexercise · easy · 10 min · practice plan

   Spread an array, push to the copy, and report both lengths.

   Passes when: #out should show 2 and 3.

5. 5.Change an object in a functionexercise · medium · 10 min · practice plan

   Show that a property changed inside a function is visible outside.

   Passes when: #out should show Grace.

6. 6.Fix the object shared instead of copiedbug fix · easy · 8 min

   A plain assignment shares the object.

   Passes when: #out should show 1 and 2.

7. 7.Fix the array sharedbug fix · easy · 8 min · practice plan

   Pushing to the second name changes the first array too.

   Passes when: #out should show 2 and 3.

8. 8.Fix the objects compared by contentsbug fix · easy · 8 min · practice plan

   Two separate objects are never equal, however alike.

   Passes when: #out should show different.

9. 9.Fix the reassignment inside a functionbug fix · easy · 8 min · practice plan

   Replacing the whole object inside a function is not visible outside.

   Passes when: #out should show Grace.

10. 10.Fix the nested object still sharedbug fix · easy · 8 min · practice plan

    Spreading copies only the top level, so the inner object is shared.

    Passes when: #out should show London.

Between them these tasks cover Primitives, References and Copying.

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