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JavaScript finally — exercises and bug fixes

5 hands-on exercises and 5 find-the-bug challenges for the JavaScript finally lesson. Every one is checked automatically in the browser — write the code, run it, and the tests tell you what still fails.

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Exercises(5)

  1. 1

    Clean up after a failure

    easy10 min

    Record the three steps in order.

  2. 2

    Clean up after success

    easy10 min

    Show that finally runs when nothing failed.

  3. 3

    Clear a loading flag

    easy10 min

    Turn the flag off whatever happens.

  4. 4

    Run before a return

    easy10 min

    Show that finally runs even when the try block returns.

  5. 5

    Use finally without catch

    medium10 min

    Clean up but let the error keep travelling.

Find the bug(5)

  1. 1

    Fix the cleanup repeated in both branches

    easy8 min

    finally does the job once instead of twice.

  2. 2

    Fix the cleanup skipped on failure

    easy8 min

    Cleanup placed in the try block is skipped when it throws.

  3. 3

    Fix the return from finally

    easy8 min

    A return in finally overrides the one in try.

  4. 4

    Fix the order recorded wrongly

    easy8 min

    finally runs last, after the catch.

  5. 5

    Fix the error swallowed by finally

    easy8 min

    The inner block should clean up but still let the error escape.

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