Throw on bad input — practice exercise

What you'll be asked to do

1. 1.Throw on bad inputexercise · easy · 10 min

   Refuse a negative age and report the message.

   Passes when: #out should show age cannot be negative.

2. 2.Stop the functionexercise · easy · 10 min · practice plan

   Show that nothing after the throw runs.

   Passes when: #out should show no value given.

3. 3.Guard a divisionexercise · easy · 10 min · practice plan

   Throw when dividing by zero and report the message.

   Passes when: #out should show cannot divide by zero.

4. 4.Return rather than throwexercise · easy · 10 min · practice plan

   A missing user is normal, so return null instead.

   Passes when: #out should show nobody found.

5. 5.Rethrow with contextexercise · medium · 10 min · practice plan

   Catch an error and throw a clearer one.

   Passes when: #out should show loading failed.

6. 6.Fix the string thrownbug fix · easy · 8 min

   A thrown string has no message property.

   Passes when: #out should show age cannot be negative.

7. 7.Fix the missing newbug fix · easy · 8 min · practice plan

   Error must be created with new to be thrown properly.

   Passes when: #out should show it broke.

8. 8.Fix the value returned instead of thrownbug fix · easy · 8 min · practice plan

   Returning a message lets the caller ignore the problem.

   Passes when: #out should show cannot divide by zero.

9. 9.Fix the throw for a normal outcomebug fix · easy · 8 min · practice plan

   A missing user is expected, so it should not throw.

   Passes when: #out should show nobody found.

10. 10.Fix the missing validationbug fix · easy · 8 min · practice plan

    Without a check the text is coerced and a wrong answer comes back.

    Passes when: #out should show width must be a number.

Between them these tasks cover throw, Error objects and Validation.

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