noControlCharactersInRegex

JavaScript (and super languages)

Summary

Rule available since: v1.0.0
Diagnostic Category: lint/suspicious/noControlCharactersInRegex
This rule is recommended, which means is enabled by default.
This rule doesn’t have a fix.
The default severity of this rule is error.
Sources:
- Same as no-control-regex

Description

Prevents from having control characters and some escape sequences that match control characters in regular expression literals.

Control characters are hidden special characters that are numbered from 0 to 31 in the ASCII system. They’re not commonly used in JavaScript text. So, if you see them in a pattern (called a regular expression), it’s probably a mistake.

The following elements of regular expression patterns are considered possible errors in typing and are therefore disallowed by this rule:

Hexadecimal character escapes from \x00 to \x1F
Unicode character escapes from \u0000 to \u001F
Unicode code point escapes from \u{0} to \u{1F}
Unescaped raw characters from U+0000 to U+001F

Control escapes such as \t and \n are allowed by this rule.

Examples

Invalid

1
 var pattern1 = /\x00/;

code-block.js:1:18 lint/suspicious/noControlCharactersInRegex ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ Unexpected control character in a regular expression.
  
  > 1 │  var pattern1 = /\x00/;
      │                  ^^^^
    2 │ 
  
  ℹ Control characters are unusual and potentially incorrect inputs, so they are disallowed.

1
 var pattern2 = /\x0C/;

code-block.js:1:18 lint/suspicious/noControlCharactersInRegex ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ Unexpected control character in a regular expression.
  
  > 1 │  var pattern2 = /\x0C/;
      │                  ^^^^
    2 │ 
  
  ℹ Control characters are unusual and potentially incorrect inputs, so they are disallowed.

1
 var pattern3 = /\x1F/;

code-block.js:1:18 lint/suspicious/noControlCharactersInRegex ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ Unexpected control character in a regular expression.
  
  > 1 │  var pattern3 = /\x1F/;
      │                  ^^^^
    2 │ 
  
  ℹ Control characters are unusual and potentially incorrect inputs, so they are disallowed.

1
 var pattern4 = /\u000C/;

code-block.js:1:18 lint/suspicious/noControlCharactersInRegex ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ Unexpected control character in a regular expression.
  
  > 1 │  var pattern4 = /\u000C/;
      │                  ^^^^^^
    2 │ 
  
  ℹ Control characters are unusual and potentially incorrect inputs, so they are disallowed.

1
 var pattern5 = /\u{C}/u;

code-block.js:1:18 lint/suspicious/noControlCharactersInRegex ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ Unexpected control character in a regular expression.
  
  > 1 │  var pattern5 = /\u{C}/u;
      │                  ^^^^^
    2 │ 
  
  ℹ Control characters are unusual and potentially incorrect inputs, so they are disallowed.

Valid

1
var pattern1 = /\x20/;
2
var pattern2 = /\u0020/;
3
var pattern3 = /\u{20}/u;
4
var pattern4 = /\t/;
5
var pattern5 = /\n/;

How to configure

1
{
2
  "linter": {
3
    "rules": {
4
      "suspicious": {
5
        "noControlCharactersInRegex": "error"
6
      }
7
    }
8
  }
9
}