Join two arrays — practice exercise

What you'll be asked to do

1. 1.Join two arraysexercise · easy · 10 min

   Combine two arrays with concat and show the result joined by commas.

   Passes when: #out should show 1,2,3,4.

2. 2.Combine with spreadexercise · easy · 10 min · practice plan

   Combine two arrays using spread instead of concat.

   Passes when: #out should show a,b,c,d.

3. 3.Choose a separatorexercise · easy · 10 min · practice plan

   Join a list of words using a space, the word and, and another space.

   Passes when: #out should show salt and pepper.

4. 4.Glue letters togetherexercise · easy · 10 min · practice plan

   Join an array of letters with no separator at all.

   Passes when: #out should show code.

5. 5.Join three arraysexercise · medium · 10 min · practice plan

   Concat three arrays in one call and show the total length.

   Passes when: #out should show 6.

6. 6.Fix concat that was thrown awaybug fix · easy · 8 min

   concat returns a new array; it does not change the original.

   Passes when: #out should show 1,2,3,4.

7. 7.Fix the array pushed instead of joinedbug fix · easy · 8 min · practice plan

   Pushing an array adds it as a single nested element.

   Passes when: #out should show a,b,c,d.

8. 8.Fix the wrong separatorbug fix · easy · 8 min · practice plan

   The list should read as a sentence, not a comma list.

   Passes when: #out should show salt and pepper.

9. 9.Fix join called without a separatorbug fix · easy · 8 min · practice plan

   The default separator adds commas between the letters.

   Passes when: #out should show code.

10. 10.Fix the spread that was missedbug fix · easy · 8 min · practice plan

    Without spread the arrays end up nested instead of merged.

    Passes when: #out should show flat 4.

Between them these tasks cover concat, join and Spread.

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