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2.4.0 • Public • Published


Turn a path string such as /user/:name into a regular expression.

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npm install path-to-regexp --save


var pathToRegexp = require('path-to-regexp')
// pathToRegexp(path, keys?, options?)
// pathToRegexp.parse(path)
// pathToRegexp.compile(path)
  • path A string, array of strings, or a regular expression.
  • keys An array to be populated with keys found in the path.
  • options
    • sensitive When true the regexp will be case sensitive. (default: false)
    • strict When true the regexp allows an optional trailing delimiter to match. (default: false)
    • end When true the regexp will match to the end of the string. (default: true)
    • start When true the regexp will match from the beginning of the string. (default: true)
    • Advanced options (use for non-pathname strings, e.g. host names):
      • delimiter The default delimiter for segments. (default: '/')
      • endsWith Optional character, or list of characters, to treat as "end" characters.
      • delimiters List of characters to consider delimiters when parsing. (default: './')
var keys = []
var re = pathToRegexp('/foo/:bar', keys)
// re = /^\/foo\/([^\/]+?)\/?$/i
// keys = [{ name: 'bar', prefix: '/', delimiter: '/', optional: false, repeat: false, pattern: '[^\\/]+?' }]

Please note: The RegExp returned by path-to-regexp is intended for ordered data (e.g. pathnames, hostnames). It does not handle arbitrary data (e.g. query strings, URL fragments, JSON, etc).


The path argument is used to define parameters and populate the list of keys.

Named Parameters

Named parameters are defined by prefixing a colon to the parameter name (:foo). By default, the parameter will match until the following path segment.

var re = pathToRegexp('/:foo/:bar')
// keys = [{ name: 'foo', prefix: '/', ... }, { name: 'bar', prefix: '/', ... }]
//=> ['/test/route', 'test', 'route']

Please note: Parameter names must be made up of "word characters" ([A-Za-z0-9_]).

Parameter Modifiers


Parameters can be suffixed with a question mark (?) to make the parameter optional.

var re = pathToRegexp('/:foo/:bar?')
// keys = [{ name: 'foo', ... }, { name: 'bar', delimiter: '/', optional: true, repeat: false }]
//=> ['/test', 'test', undefined]
//=> ['/test', 'test', 'route']

Tip: If the parameter is the only value in the segment, the prefix is also optional.

Zero or more

Parameters can be suffixed with an asterisk (*) to denote a zero or more parameter matches. The prefix is taken into account for each match.

var re = pathToRegexp('/:foo*')
// keys = [{ name: 'foo', delimiter: '/', optional: true, repeat: true }]
//=> ['/', undefined]
//=> ['/bar/baz', 'bar/baz']
One or more

Parameters can be suffixed with a plus sign (+) to denote a one or more parameter matches. The prefix is taken into account for each match.

var re = pathToRegexp('/:foo+')
// keys = [{ name: 'foo', delimiter: '/', optional: false, repeat: true }]
//=> null
//=> ['/bar/baz', 'bar/baz']

Custom Matching Parameters

All parameters can be provided a custom regexp, which overrides the default match ([^\/]+). For example, you can match digits in the path:

var re = pathToRegexp('/icon-:foo(\\d+).png')
// keys = [{ name: 'foo', ... }]
//=> ['/icon-123.png', '123']
//=> null

Please note: Backslashes need to be escaped with another backslash in strings.

Unnamed Parameters

It is possible to write an unnamed parameter that only consists of a matching group. It works the same as a named parameter, except it will be numerically indexed.

var re = pathToRegexp('/:foo/(.*)')
// keys = [{ name: 'foo', ... }, { name: 0, ... }]
//=> ['/test/route', 'test', 'route']


The parse function is exposed via pathToRegexp.parse. This will return an array of strings and keys.

var tokens = pathToRegexp.parse('/route/:foo/(.*)')
//=> "/route"
//=> { name: 'foo', prefix: '/', delimiter: '/', optional: false, repeat: false, pattern: '[^\\/]+?' }
//=> { name: 0, prefix: '/', delimiter: '/', optional: false, repeat: false, pattern: '.*' }

Note: This method only works with strings.

Compile ("Reverse" Path-To-RegExp)

Path-To-RegExp exposes a compile function for transforming a string into a valid path.

var toPath = pathToRegexp.compile('/user/:id')
toPath({ id: 123 }) //=> "/user/123"
toPath({ id: 'café' }) //=> "/user/caf%C3%A9"
toPath({ id: '/' }) //=> "/user/%2F"
toPath({ id: ':/' }) //=> "/user/%3A%2F"
toPath({ id: ':/' }, { encode: (value, token) => value }) //=> "/user/:/"
var toPathRepeated = pathToRegexp.compile('/:segment+')
toPathRepeated({ segment: 'foo' }) //=> "/foo"
toPathRepeated({ segment: ['a', 'b', 'c'] }) //=> "/a/b/c"
var toPathRegexp = pathToRegexp.compile('/user/:id(\\d+)')
toPathRegexp({ id: 123 }) //=> "/user/123"
toPathRegexp({ id: '123' }) //=> "/user/123"
toPathRegexp({ id: 'abc' }) //=> Throws `TypeError`.

Note: The generated function will throw on invalid input. It will do all necessary checks to ensure the generated path is valid. This method only works with strings.

Working with Tokens

Path-To-RegExp exposes the two functions used internally that accept an array of tokens.

  • pathToRegexp.tokensToRegExp(tokens, keys?, options?) Transform an array of tokens into a matching regular expression.
  • pathToRegexp.tokensToFunction(tokens) Transform an array of tokens into a path generator function.

Token Information

  • name The name of the token (string for named or number for index)
  • prefix The prefix character for the segment (/ or .)
  • delimiter The delimiter for the segment (same as prefix or /)
  • optional Indicates the token is optional (boolean)
  • repeat Indicates the token is repeated (boolean)
  • partial Indicates this token is a partial path segment (boolean)
  • pattern The RegExp used to match this token (string)

Compatibility with Express <= 4.x

Path-To-RegExp breaks compatibility with Express <= 4.x:

  • RegExp special characters can only be used in a parameter
    • Express.js 4.x used all RegExp special characters regardless of position - this considered a bug
  • Parameters have suffixes that augment meaning - *, + and ?. E.g. /:user*
  • No wildcard asterisk (*) - use parameters instead ((.*))


Includes a .d.ts file for TypeScript users.

Live Demo

You can see a live demo of this library in use at express-route-tester.




npm i path-to-regexp

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