Chain two steps — practice exercise

What you'll be asked to do

1. 1.Chain two stepsexercise · easy · 10 min

   Multiply a value in one step and report it in the next.

   Passes when: #out should show 10.

2. 2.Build a string across stepsexercise · easy · 10 min · practice plan

   Add a letter in each step and report the result.

   Passes when: #out should show abc.

3. 3.Wait for another promiseexercise · easy · 10 min · practice plan

   Return a promise from a step so the chain waits for it.

   Passes when: #out should show one two.

4. 4.Catch at the endexercise · easy · 10 min · practice plan

   Throw in the middle of a chain and catch it at the end.

   Passes when: #out should show caught: broke.

5. 5.Recover and continueexercise · medium · 10 min · practice plan

   Catch a rejection, return a value, and carry on down the chain.

   Passes when: #out should show recovered.

6. 6.Fix the missing returnbug fix · easy · 8 min

   Without a return the next step receives undefined.

   Passes when: #out should show 10.

7. 7.Fix the nested thenbug fix · easy · 8 min · practice plan

   Nesting rebuilds callback hell; the promise should be returned instead.

   Passes when: #out should show one two.

8. 8.Fix the catch placed too earlybug fix · easy · 8 min · practice plan

   A catch before the failing step cannot catch it.

   Passes when: #out should show caught: broke.

9. 9.Fix the steps run separatelybug fix · easy · 8 min · practice plan

   Calling then twice on the same promise does not chain them.

   Passes when: #out should show abc.

10. 10.Fix the value used after the chainbug fix · easy · 8 min · practice plan

    The chain has not finished when the line below runs.

    Passes when: #out should show done.

Between them these tasks cover Chaining, Returning values and Flattening.

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