List the keys — practice exercise

What you'll be asked to do

1. 1.List the keysexercise · easy · 10 min

   Spread the keys into an array and join them.

   Passes when: #out should show Ada,Grace.

2. 2.Total the valuesexercise · easy · 10 min · practice plan

   Add up every value in the Map.

   Passes when: #out should show 185.

3. 3.Loop with forEachexercise · easy · 10 min · practice plan

   Build a line using the value and the key.

   Passes when: #out should show Ada scored 90.

4. 4.Convert to an objectexercise · easy · 10 min · practice plan

   Turn the Map into a plain object and read a property.

   Passes when: #out should show 90.

5. 5.Convert from an objectexercise · medium · 10 min · practice plan

   Build a Map from an object and read a value.

   Passes when: #out should show dark.

6. 6.Fix the forEach arguments swappedbug fix · easy · 8 min

   In a Map forEach the value comes first, then the key.

   Passes when: #out should show Ada scored 90.

7. 7.Fix map called on the iteratorbug fix · easy · 8 min · practice plan

   keys returns an iterator, which has no array methods.

   Passes when: #out should show Ada,Grace.

8. 8.Fix keys totalled instead of valuesbug fix · easy · 8 min · practice plan

   The numbers are the values, not the keys.

   Passes when: #out should show 185.

9. 9.Fix the Map spread directly into an objectbug fix · easy · 8 min · practice plan

   Object.fromEntries is what converts the pairs.

   Passes when: #out should show 90.

10. 10.Fix the object passed straight to Mapbug fix · easy · 8 min · practice plan

    A Map needs pairs, which Object.entries produces.

    Passes when: #out should show dark.

Between them these tasks cover keys and values, forEach and Conversion.

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