Express-style path to regexp
TypeScript JavaScript


Turn an Express-style 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 An Express-style string, an array of strings, or a regular expression.
  • keys An array to be populated with the keys found in the path.
  • options
    • sensitive When true the route will be case sensitive. (default: false)
    • strict When false the trailing slash is optional. (default: false)
    • end When false the path will match at the beginning. (default: true)
    • delimiter Set the default delimiter for repeat parameters. (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 use with pathnames or hostnames. It can not handle the query strings or fragments of a URL.


The path string can be used to define parameters and populate the 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)
// keys = [{ name: 'foo', prefix: '/', ... }, { name: 'bar', prefix: '/', ... }]

//=> ['/test/route', 'test', 'route']

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

var re = pathToRegexp('/(apple-)?icon-:res(\\d+).png', keys)
// keys = [{ name: 0, prefix: '/', ... }, { name: 'res', prefix: '', ... }]

//=> ['/icon-76.png', undefined, '76']

Modified Parameters


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

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

//=> ['/test', 'test', undefined]

//=> ['/test', 'test', 'route']
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)
// 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)
// keys = [{ name: 'foo', delimiter: '/', optional: false, repeat: true }]

//=> null

//=> ['/bar/baz', 'bar/baz']

Custom Match Parameters

All parameters can be provided a custom regexp, which overrides the default ([^\/]+).

var re = pathToRegexp('/:foo(\\d+)', keys)
// keys = [{ name: 'foo', ... }]

//=> ['/123', '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)
// keys = [{ name: 'foo', ... }, { name: 0, ... }]

//=> ['/test/route', 'test', 'route']


An asterisk can be used for matching everything. It is equivalent to an unnamed matching group of (.*).

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

//=> ['/foo/bar/baz', 'bar/baz']


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 Express-style strings.

Compile ("Reverse" Path-To-RegExp)

Path-To-RegExp exposes a compile function for transforming an Express-style path 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"
toPath({ id: ':' }, { pretty: true }) //=> "/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, 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)
  • asterisk Indicates the token is an * match (boolean)

Compatibility with Express <= 4.x

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

  • No longer a direct conversion to a RegExp with sugar on top - it's a path matcher with named and unnamed matching groups
    • It's unlikely you previously abused this feature, it's rare and you could always use a RegExp instead
  • All matching RegExp special characters can be used in a matching group. E.g. /:user(.*)
    • Other RegExp features are not support - no nested matching groups, non-capturing groups or look aheads
  • Parameters have suffixes that augment meaning - *, + and ?. E.g. /:user*


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.