Build a string with forEach — practice exercise

What you'll be asked to do

1. 1.Build a string with forEachexercise · easy · 10 min

   Use forEach to build a dash-separated string of the values.

   Passes when: #out should show a-b-c-.

2. 2.Add up with forEachexercise · easy · 10 min · practice plan

   Use forEach to total a list of numbers.

   Passes when: #out should show 60.

3. 3.Use the indexexercise · easy · 10 min · practice plan

   Number each name starting at 1, separated by spaces.

   Passes when: #out should show 1.Ada 2.Grace.

4. 4.Count matching valuesexercise · easy · 10 min · practice plan

   Use forEach to count how many numbers are above 10.

   Passes when: #out should show 2.

5. 5.Show forEach returns nothingexercise · medium · 10 min · practice plan

   Store the result of forEach and show its type.

   Passes when: #out should show undefined.

6. 6.Fix the result of forEach being usedbug fix · easy · 8 min

   forEach returns nothing, so the doubled values were lost.

   Passes when: #out should show 2,4,6.

7. 7.Fix the total declared insidebug fix · easy · 8 min · practice plan

   Declaring the total inside the callback resets it every time.

   Passes when: #out should show 60.

8. 8.Fix the arguments in the wrong orderbug fix · easy · 8 min · practice plan

   The value comes first and the index second, so the labels came out backwards.

   Passes when: #out should show 0:a 1:b.

9. 9.Fix the numbering starting at zerobug fix · easy · 8 min · practice plan

   The list should be numbered from 1.

   Passes when: #out should show 1.Ada 2.Grace.

10. 10.Fix the early exit that never happensbug fix · easy · 8 min · practice plan

    return inside forEach only skips one turn, so the count keeps rising.

    Passes when: #out should show stopped at 2.

Between them these tasks cover forEach, Callbacks and Index argument.

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