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JavaScript Variables — exercises and bug fixes

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

    Declare a variable with let

    easy10 min

    Declare a variable named score, set it to 42, and show it.

    • Declare score with let.
    • #out should show 42.
  2. 2

    Use const for a fixed value

    easy10 min

    Store the site name in a constant and display it.

  3. 3

    Reassign a let variable

    easy10 min

    Start count at 5, reassign it to 9, then show the final value.

  4. 4

    Combine two variables

    easy10 min

    Join a first and last name into one full name.

  5. 5

    Swap two variables

    medium10 min

    Given a = 1 and b = 2, swap them and show them as "2,1".

Find the bug(5)

  1. 1

    Fix the misspelled variable

    easy8 min

    The value never appears because the variable name is wrong.

  2. 2

    Fix the reassigned constant

    easy8 min

    This code throws because a const is being reassigned.

  3. 3

    Fix the variable used too early

    easy8 min

    The variable is read before it is declared.

  4. 4

    Fix the missing quotes

    easy8 min

    A text value was written without quotes, so it is treated as a variable.

  5. 5

    Fix the wrong concatenation

    easy8 min

    The full name is missing the space between the two parts.

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