eslint/docs/rules/no-invalid-regexp.md

   1 # disallow invalid regular expression strings in `RegExp` constructors (no-invalid-regexp)
   2
   3 An invalid pattern in a regular expression literal is a `SyntaxError` when the code is parsed, but an invalid string in `RegExp` constructors throws a `SyntaxError` only when the code is executed.
   4
   5 ## Rule Details
   6
   7 This rule disallows invalid regular expression strings in `RegExp` constructors.
   8
   9 Examples of **incorrect** code for this rule:
  10
  11 ```js
  12 /*eslint no-invalid-regexp: "error"*/
  13
  14 RegExp('[')
  15
  16 RegExp('.', 'z')
  17
  18 new RegExp('\\')
  19 ```
  20
  21 Examples of **correct** code for this rule:
  22
  23 ```js
  24 /*eslint no-invalid-regexp: "error"*/
  25
  26 RegExp('.')
  27
  28 new RegExp
  29
  30 this.RegExp('[')
  31 ```
  32
  33 Please note that this rule validates regular expressions per the latest ECMAScript specification, regardless of your parser settings.
  34
  35 If you want to allow additional constructor flags for any reason, you can specify them using the `allowConstructorFlags` option. These flags will then be ignored by the rule.
  36
  37 ## Options
  38
  39 This rule has an object option for exceptions:
  40
  41 * `"allowConstructorFlags"` is an array of flags
  42
  43 ### allowConstructorFlags
  44
  45 Examples of **correct** code for this rule with the `{ "allowConstructorFlags": ["a", "z"] }` option:
  46
  47 ```js
  48 /*eslint no-invalid-regexp: ["error", { "allowConstructorFlags": ["a", "z"] }]*/
  49
  50 new RegExp('.', 'a')
  51
  52 new RegExp('.', 'az')
  53 ```
  54
  55 ## Further Reading
  56
  57 * [Annotated ES5 §7.8.5 - Regular Expression Literals](https://es5.github.io/#x7.8.5)