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JavaScript Debounce — exercises and bug fixes

5 hands-on exercises and 5 find-the-bug challenges for the JavaScript Debounce 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

    Build a debounce wrapper

    easy10 min

    Write debounce and confirm no call has run yet after several calls.

  2. 2

    Show each call resets the timer

    easy10 min

    Confirm nothing has been received yet after three rapid calls.

  3. 3

    Simulate a search box

    easy10 min

    Type several characters and confirm no search ran yet.

  4. 4

    Simulate rapid resize events

    easy10 min

    Fire many resize calls and confirm layout has not run yet.

  5. 5

    Pass arguments through the wrapper

    medium10 min

    Confirm the debounced function accepts arguments without error.

Find the bug(5)

  1. 1

    Fix the timer never cleared

    easy8 min

    Without clearTimeout, every call schedules its own run instead of collapsing into one.

  2. 2

    Fix the function called immediately

    easy8 min

    The function should be scheduled, not run right away.

  3. 3

    Fix the timer variable shared across instances

    easy8 min

    Two separately created debounced functions should not share one timer — here the second call cancels the first.

  4. 4

    Fix the arguments never forwarded

    easy8 min

    The wrapped function should receive what it was called with.

  5. 5

    Fix the wrapper missing its return

    easy8 min

    debounce must return the wrapped function for it to be usable.

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