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noMisleadingCharacterClass (since v1.5.0)

Diagnostic Category: lint/suspicious/noMisleadingCharacterClass

Sources:

Disallow characters made with multiple code points in character class syntax.

Unicode includes the characters which are made with multiple code points. e.g. Á, 🇯🇵, 👨‍👩‍👦. A RegExp character class /[abc]/ cannot handle characters with multiple code points. For example, the character ❇️ consists of two code points: ❇ (U+2747) and VARIATION SELECTOR-16 (U+FE0F). If this character is in a RegExp character class, it will match to either ❇ or VARIATION SELECTOR-16 rather than ❇️. This rule reports the regular expressions which include multiple code point characters in character class syntax.

Examples

Section titled Examples

Invalid

Section titled Invalid
/^[Á]$/u;
suspicious/noMisleadingCharacterClass.js:1:1 lint/suspicious/noMisleadingCharacterClass ━━━━━━━━━━━━

  ✖ Unexpected combined character in the character class.
  
  > 1 │ /^[Á]$/u;
      │ ^^^^^^^^
    2 │ 
  

/^[❇️]$/u;
suspicious/noMisleadingCharacterClass.js:1:1 lint/suspicious/noMisleadingCharacterClass ━━━━━━━━━━━━

  ✖ Unexpected combined character in the character class.
  
  > 1 │ /^[❇️]$/u;
      │ ^^^^^^^^
    2 │ 
  

/^[👶🏻]$/u;
suspicious/noMisleadingCharacterClass.js:1:1 lint/suspicious/noMisleadingCharacterClass ━━━━━━━━━━━━

  ✖ Unexpected modified Emoji in the character class. 
  
  > 1 │ /^[👶🏻]$/u;
      │ ^^^^^^^^^^^
    2 │ 
  

/^[🇯🇵]$/u;
suspicious/noMisleadingCharacterClass.js:1:1 lint/suspicious/noMisleadingCharacterClass ━━━━━━━━━━━━

  ✖ Regional indicator symbol characters should not be used in the character class.
  
  > 1 │ /^[🇯🇵]$/u;
      │ ^^^^^^^^^
    2 │ 
  

/^[👨‍👩‍👦]$/u;
suspicious/noMisleadingCharacterClass.js:1:1 lint/suspicious/noMisleadingCharacterClass ━━━━━━━━━━━━

  ✖ Unexpected joined character sequence in character class.
  
  > 1 │ /^[👨‍👩‍👦]$/u;
      │ ^^^^^^^^^^^^^
    2 │ 
  

/^[👍]$/; // surrogate pair without u flag
suspicious/noMisleadingCharacterClass.js:1:1 lint/suspicious/noMisleadingCharacterClass  FIXABLE  ━━━━━━━━━━

  ✖ Unexpected surrogate pair in character class. Use the 'u' flag.
  
  > 1 │ /^[👍]$/; // surrogate pair without u flag
      │ ^^^^^^^^
    2 │ 
  
  ℹ Safe fix: Add unicode u flag to regex
  
    1 │ /^[👍]$/u;·//·surrogate·pair·without·u·flag
      │         +

Valid

Section titled Valid
/^[abc]$/;
/^[👍]$/u;
/^[\q{👶🏻}]$/v;
Section titled Related links