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noEmptyCharacterClassInRegex (since v1.3.0)

Diagnostic Category: lint/correctness/noEmptyCharacterClassInRegex

Sources:

Disallow empty character classes in regular expression literals.

Empty character classes don’t match anything. In contrast, negated empty classes match any character. They are often the result of a typing mistake.

Examples

Section titled Examples

Invalid

Section titled Invalid
/^a[]/.test("a"); // false
correctness/noEmptyCharacterClassInRegex.js:1:4 lint/correctness/noEmptyCharacterClassInRegex ━━━━━━━━━━

  ✖ The regular expression includes this empty character class.
  
  > 1 │ /^a[]/.test("a"); // false
      │    ^^
    2 │ 
  
  ℹ Empty character classes don't match anything.
    If you want to match against [, escape it \[.
    Otherwise, remove the character class or fill it.
  

/^a[^]/.test("ax"); // true
correctness/noEmptyCharacterClassInRegex.js:1:4 lint/correctness/noEmptyCharacterClassInRegex ━━━━━━━━━━

  ✖ The regular expression includes this negated empty character class.
  
  > 1 │ /^a[^]/.test("ax"); // true
      │    ^^^
    2 │ 
  
  ℹ Negated empty character classes match anything.
    If you want to match against [, escape it \[.
    Otherwise, remove the character class or fill it.

Valid

Section titled Valid
/^a[xy]/.test("ay"); // true
/^a[^xy]/.test("ab"); // true
/^a\[]/.test("a[]"); // true
Section titled Related links