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JavaScript Regex Validation — exercises and bug fixes

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

    Accept digits only

    easy10 min

    Check the value is nothing but digits.

  2. 2

    Reject mixed input

    easy10 min

    Check a value with a letter is refused.

  3. 3

    Check a fixed format code

    easy10 min

    Accept three capitals followed by three digits.

  4. 4

    Allow an optional prefix

    easy10 min

    Accept the number with or without a leading plus.

  5. 5

    Combine with a range check

    medium10 min

    Check the shape with a pattern and the range with a number.

Find the bug(5)

  1. 1

    Fix the unanchored digit check

    easy8 min

    Without anchors a mixed value passes.

  2. 2

    Fix the case-sensitive code check

    easy8 min

    The code requires capitals, so lowercase must be refused.

  3. 3

    Fix the range checked by pattern

    easy8 min

    A pattern cannot express a numeric range, so check the number.

  4. 4

    Fix the plus treated as a quantifier

    easy8 min

    A literal plus must be escaped.

  5. 5

    Fix the empty value accepted

    easy8 min

    A star allows an empty string, which should be refused.

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