698fa0bb47
## Review A dedicated reviewer checked the rule description successfully for: - [ ] logical errors and incorrect information - [ ] information gaps and missing content - [ ] text style and tone - [ ] PR summary and labels follow [the guidelines](https://github.com/SonarSource/rspec/#to-modify-an-existing-rule)
36 lines
1.5 KiB
Plaintext
36 lines
1.5 KiB
Plaintext
== Why is this an issue?
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include::../description.adoc[]
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Character ranges can also create duplicates when used with character class escapes. These are a type of escape sequence used in regular expressions to represent a specific set of characters. They are denoted by a backslash followed by a specific letter, such as `++\d++` for digits, `++\w++` for word characters, or `++\s++` for whitespace characters. For example, the character class escape `++\d++` is equivalent to the character range `++[0-9]++`, and the escape `++\w++` is equivalent to `++[a-zA-Z0-9_]++`.
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== How to fix it
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Remove the extra character, character range, or character class escape.
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=== Code examples
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==== Noncompliant code example
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[source,javascript,diff-id=1,diff-type=noncompliant]
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----
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/[0-99]/ // Noncompliant, this won't actually match strings with two digits
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/[0-9.-_]/ // Noncompliant, .-_ is a range that already contains 0-9 (as well as various other characters such as capital letters)
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/[a-z0-9\d]/ // Noncompliant, \d matches a digit and is equivalent to [0-9]
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----
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==== Compliant solution
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[source,javascript,diff-id=1,diff-type=compliant]
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----
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/[0-9]{1,2}/
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/[0-9.\-_]/
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/[a-z\d]/
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----
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== Resources
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=== Documentation
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* MDN web docs - https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_expressions/Character_classes[Character classes]
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* MDN web docs - https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Regular_expressions/Character_class_escape[Character class escape]
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