---
source: crates/biome_js_analyze/tests/spec_tests.rs
expression: invalid.js
---
# Input
```jsx
/^abc[]/;
/foo[]bar/;
if (foo.match(/^abc[]/)) {}
if (/^abc[]/.test(foo)) {}
/[]]/;
/\[[]/;
/\[\[\]a-z[]/;
/[]]/d;
/[(]\u{0}*[]/u;
/[]/v;
/[[]]/v;
/[[a][]]/v;
/[a[[b[]c]]d]/v;
/[a--[]]/v;
/[[]--b]/v;
/[a&&[]]/v;
/[[]&&b]/v;
// negated empty class
/[^]/;
/\[][^]/;
/[\u200E\u2066-\u2069][]/gu;
```

# Diagnostics
```
invalid.js:1:6 lint/correctness/noEmptyCharacterClassInRegex ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ! The regular expression includes this empty character class.
  
  > 1 │ /^abc[]/;
      │      ^^
    2 │ /foo[]bar/;
    3 │ if (foo.match(/^abc[]/)) {}
  
  i Empty character classes don't match anything.
    If you want to match against [, escape it \[.
    Otherwise, remove the character class or fill it.
  

```

```
invalid.js:2:5 lint/correctness/noEmptyCharacterClassInRegex ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ! The regular expression includes this empty character class.
  
    1 │ /^abc[]/;
  > 2 │ /foo[]bar/;
      │     ^^
    3 │ if (foo.match(/^abc[]/)) {}
    4 │ if (/^abc[]/.test(foo)) {}
  
  i Empty character classes don't match anything.
    If you want to match against [, escape it \[.
    Otherwise, remove the character class or fill it.
  

```

```
invalid.js:3:20 lint/correctness/noEmptyCharacterClassInRegex ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ! The regular expression includes this empty character class.
  
    1 │ /^abc[]/;
    2 │ /foo[]bar/;
  > 3 │ if (foo.match(/^abc[]/)) {}
      │                    ^^
    4 │ if (/^abc[]/.test(foo)) {}
    5 │ /[]]/;
  
  i Empty character classes don't match anything.
    If you want to match against [, escape it \[.
    Otherwise, remove the character class or fill it.
  

```

```
invalid.js:4:10 lint/correctness/noEmptyCharacterClassInRegex ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ! The regular expression includes this empty character class.
  
    2 │ /foo[]bar/;
    3 │ if (foo.match(/^abc[]/)) {}
  > 4 │ if (/^abc[]/.test(foo)) {}
      │          ^^
    5 │ /[]]/;
    6 │ /\[[]/;
  
  i Empty character classes don't match anything.
    If you want to match against [, escape it \[.
    Otherwise, remove the character class or fill it.
  

```

```
invalid.js:5:2 lint/correctness/noEmptyCharacterClassInRegex ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ! The regular expression includes this empty character class.
  
    3 │ if (foo.match(/^abc[]/)) {}
    4 │ if (/^abc[]/.test(foo)) {}
  > 5 │ /[]]/;
      │  ^^
    6 │ /\[[]/;
    7 │ /\[\[\]a-z[]/;
  
  i Empty character classes don't match anything.
    If you want to match against [, escape it \[.
    Otherwise, remove the character class or fill it.
  

```

```
invalid.js:6:4 lint/correctness/noEmptyCharacterClassInRegex ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ! The regular expression includes this empty character class.
  
    4 │ if (/^abc[]/.test(foo)) {}
    5 │ /[]]/;
  > 6 │ /\[[]/;
      │    ^^
    7 │ /\[\[\]a-z[]/;
    8 │ /[]]/d;
  
  i Empty character classes don't match anything.
    If you want to match against [, escape it \[.
    Otherwise, remove the character class or fill it.
  

```

```
invalid.js:7:11 lint/correctness/noEmptyCharacterClassInRegex ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ! The regular expression includes this empty character class.
  
    5 │ /[]]/;
    6 │ /\[[]/;
  > 7 │ /\[\[\]a-z[]/;
      │           ^^
    8 │ /[]]/d;
    9 │ /[(]\u{0}*[]/u;
  
  i Empty character classes don't match anything.
    If you want to match against [, escape it \[.
    Otherwise, remove the character class or fill it.
  

```

```
invalid.js:8:2 lint/correctness/noEmptyCharacterClassInRegex ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ! The regular expression includes this empty character class.
  
     6 │ /\[[]/;
     7 │ /\[\[\]a-z[]/;
   > 8 │ /[]]/d;
       │  ^^
     9 │ /[(]\u{0}*[]/u;
    10 │ /[]/v;
  
  i Empty character classes don't match anything.
    If you want to match against [, escape it \[.
    Otherwise, remove the character class or fill it.
  

```

```
invalid.js:9:11 lint/correctness/noEmptyCharacterClassInRegex ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ! The regular expression includes this empty character class.
  
     7 │ /\[\[\]a-z[]/;
     8 │ /[]]/d;
   > 9 │ /[(]\u{0}*[]/u;
       │           ^^
    10 │ /[]/v;
    11 │ /[[]]/v;
  
  i Empty character classes don't match anything.
    If you want to match against [, escape it \[.
    Otherwise, remove the character class or fill it.
  

```

```
invalid.js:10:2 lint/correctness/noEmptyCharacterClassInRegex ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ! The regular expression includes this empty character class.
  
     8 │ /[]]/d;
     9 │ /[(]\u{0}*[]/u;
  > 10 │ /[]/v;
       │  ^^
    11 │ /[[]]/v;
    12 │ /[[a][]]/v;
  
  i Empty character classes don't match anything.
    If you want to match against [, escape it \[.
    Otherwise, remove the character class or fill it.
  

```

```
invalid.js:11:3 lint/correctness/noEmptyCharacterClassInRegex ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ! The regular expression includes this empty character class.
  
     9 │ /[(]\u{0}*[]/u;
    10 │ /[]/v;
  > 11 │ /[[]]/v;
       │   ^^
    12 │ /[[a][]]/v;
    13 │ /[a[[b[]c]]d]/v;
  
  i Empty character classes don't match anything.
    If you want to match against [, escape it \[.
    Otherwise, remove the character class or fill it.
  

```

```
invalid.js:12:6 lint/correctness/noEmptyCharacterClassInRegex ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ! The regular expression includes this empty character class.
  
    10 │ /[]/v;
    11 │ /[[]]/v;
  > 12 │ /[[a][]]/v;
       │      ^^
    13 │ /[a[[b[]c]]d]/v;
    14 │ /[a--[]]/v;
  
  i Empty character classes don't match anything.
    If you want to match against [, escape it \[.
    Otherwise, remove the character class or fill it.
  

```

```
invalid.js:13:7 lint/correctness/noEmptyCharacterClassInRegex ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ! The regular expression includes this empty character class.
  
    11 │ /[[]]/v;
    12 │ /[[a][]]/v;
  > 13 │ /[a[[b[]c]]d]/v;
       │       ^^
    14 │ /[a--[]]/v;
    15 │ /[[]--b]/v;
  
  i Empty character classes don't match anything.
    If you want to match against [, escape it \[.
    Otherwise, remove the character class or fill it.
  

```

```
invalid.js:14:6 lint/correctness/noEmptyCharacterClassInRegex ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ! The regular expression includes this empty character class.
  
    12 │ /[[a][]]/v;
    13 │ /[a[[b[]c]]d]/v;
  > 14 │ /[a--[]]/v;
       │      ^^
    15 │ /[[]--b]/v;
    16 │ /[a&&[]]/v;
  
  i Empty character classes don't match anything.
    If you want to match against [, escape it \[.
    Otherwise, remove the character class or fill it.
  

```

```
invalid.js:15:3 lint/correctness/noEmptyCharacterClassInRegex ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ! The regular expression includes this empty character class.
  
    13 │ /[a[[b[]c]]d]/v;
    14 │ /[a--[]]/v;
  > 15 │ /[[]--b]/v;
       │   ^^
    16 │ /[a&&[]]/v;
    17 │ /[[]&&b]/v;
  
  i Empty character classes don't match anything.
    If you want to match against [, escape it \[.
    Otherwise, remove the character class or fill it.
  

```

```
invalid.js:16:6 lint/correctness/noEmptyCharacterClassInRegex ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ! The regular expression includes this empty character class.
  
    14 │ /[a--[]]/v;
    15 │ /[[]--b]/v;
  > 16 │ /[a&&[]]/v;
       │      ^^
    17 │ /[[]&&b]/v;
    18 │ // negated empty class
  
  i Empty character classes don't match anything.
    If you want to match against [, escape it \[.
    Otherwise, remove the character class or fill it.
  

```

```
invalid.js:17:3 lint/correctness/noEmptyCharacterClassInRegex ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ! The regular expression includes this empty character class.
  
    15 │ /[[]--b]/v;
    16 │ /[a&&[]]/v;
  > 17 │ /[[]&&b]/v;
       │   ^^
    18 │ // negated empty class
    19 │ /[^]/;
  
  i Empty character classes don't match anything.
    If you want to match against [, escape it \[.
    Otherwise, remove the character class or fill it.
  

```

```
invalid.js:19:2 lint/correctness/noEmptyCharacterClassInRegex ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ! The regular expression includes this negated empty character class.
  
    17 │ /[[]&&b]/v;
    18 │ // negated empty class
  > 19 │ /[^]/;
       │  ^^^
    20 │ /\[][^]/;
    21 │ /[\u200E\u2066-\u2069][]/gu;
  
  i Negated empty character classes match anything.
    If you want to match against [, escape it \[.
    Otherwise, remove the character class or fill it.
  

```

```
invalid.js:20:5 lint/correctness/noEmptyCharacterClassInRegex ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ! The regular expression includes this negated empty character class.
  
    18 │ // negated empty class
    19 │ /[^]/;
  > 20 │ /\[][^]/;
       │     ^^^
    21 │ /[\u200E\u2066-\u2069][]/gu;
  
  i Negated empty character classes match anything.
    If you want to match against [, escape it \[.
    Otherwise, remove the character class or fill it.
  

```

```
invalid.js:21:23 lint/correctness/noEmptyCharacterClassInRegex ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ! The regular expression includes this empty character class.
  
    19 │ /[^]/;
    20 │ /\[][^]/;
  > 21 │ /[\u200E\u2066-\u2069][]/gu;
       │                       ^^
  
  i Empty character classes don't match anything.
    If you want to match against [, escape it \[.
    Otherwise, remove the character class or fill it.
  

```