Turn an Express-style path string such as /user/:name into a regular expression.

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)

var keys = [] var re = pathToRegexp('/foo/:bar', keys) // re = /^\/foo\/([^\/]+?)\/?$/i // keys = [{ name: 'bar', prefix: '/', delimiter: '/', optional: false, repeat: false, pattern: '[^\\/]+?' }]

The path string can be used to define parameters and populate the keys.

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

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

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

Parameters can be suffixed with a question mark (?) to make the parameter optional. This will also make any the prefixed path delimiter optional (/ or .).

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

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

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

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

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

All parameters can be provided a custom regexp, which overrides the default ([^\/]+). Please note: Backslashes need to be escaped with another backslash in strings.

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

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, ... }] re.exec('/test/route') //=> ['/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', ... }] re.exec('/foo/bar/baz') //=> ['/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/(.*)') console.log(tokens[0]) //=> "/route" console.log(tokens[1]) //=> { name: 'foo', prefix: '/', delimiter: '/', optional: false, repeat: false, pattern: '[^\\/]+?' } console.log(tokens[2]) //=> { name: 0, prefix: '/', delimiter: '/', optional: false, repeat: false, pattern: '.*' }

Note: This method only works with Express-style strings.

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: '/' }) //=> "%2F" 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.

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.

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*

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

MIT