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What is JavaScript — exercises and bug fixes

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

    Make the page say something

    easy10 min

    Use JavaScript to put the word "running" into #out.

  2. 2

    Do a calculation in the page

    easy10 min

    Work out 6 times 7 and show the result.

  3. 3

    Read something from the page

    easy10 min

    Read the heading's text and show it.

  4. 4

    Change a style from JavaScript

    easy10 min

    Set #out's colour to red, then report "styled".

  5. 5

    Store and reuse a value

    medium10 min

    Store a browser fact in a variable and show "dynamic".

Find the bug(5)

  1. 1

    Fix the wrong selector

    easy8 min

    The code targets an element that does not exist.

  2. 2

    Fix the misspelled property

    easy8 min

    textContent is spelled wrong, so nothing appears.

  3. 3

    Fix the missing quotes

    easy8 min

    The text is unquoted, so JavaScript looks for a variable.

  4. 4

    Fix the wrong method name

    easy8 min

    querySelectorAll returns a list, not one element.

  5. 5

    Fix the reversed assignment

    easy8 min

    The assignment is written backwards.

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