Intercept a read — practice exercise

What you'll be asked to do

1. 1.Intercept a readexercise · easy · 10 min

   Create a Proxy that passes reads straight through.

   Passes when: #out should show Ada.

2. 2.Log every readexercise · easy · 10 min · practice plan

   Record which keys were read through the proxy.

   Passes when: #out should show name,age.

3. 3.Validate a writeexercise · easy · 10 min · practice plan

   Reject a negative age through a set trap.

   Passes when: #out should show 0.

4. 4.Supply a default for a missing keyexercise · easy · 10 min · practice plan

   Return a fallback string for any property not on the object.

   Passes when: #out should show not set.

5. 5.Use the has trapexercise · medium · 10 min · practice plan

   Make one extra key always report as present.

   Passes when: #out should show true and false.

6. 6.Fix the set trap that forgets to store the valuebug fix · easy · 8 min

   The trap must actually assign the value on the target.

   Passes when: #out should show 40.

7. 7.Fix the set trap missing its return valuebug fix · easy · 8 min · practice plan

   A set trap must return true, or the assignment is reported as failed even though the value was stored.

   Passes when: #out should show assignment accepted.

8. 8.Fix the validation checking the wrong keybug fix · easy · 8 min · practice plan

   The validation compares against the wrong property name.

   Passes when: #out should show 0.

9. 9.Fix the direct target read counted as a proxy readbug fix · easy · 8 min · practice plan

   Reading the original target bypasses the trap entirely, so nothing is counted.

   Passes when: #out should show 2 trapped.

10. 10.Fix the has trap that ignores the real objectbug fix · easy · 8 min · practice plan

    Any key not specially handled should fall back to checking the object.

    Passes when: #out should show true.

Between them these tasks cover Proxy, get and set traps and Validation.

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