Path-to-RegExp

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

Installation

npm install path-to-regexp --save

Usage

var pathToRegexp = require('path-to-regexp')

// pathToRegexp(path, keys, options)
// pathToRegexp.parse(path)
// pathToRegexp.compile(path)

• path A string in the express format, an array of strings, or a regular expression.
• keys An array to be populated with the keys present in the url.
• 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: '[^\\/]+?' }]

Parameters

The path has the ability to define parameters and automatically populate the keys array.

Named Parameters

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

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

re.exec('/test/route')
//=> ['/test/route', 'test', 'route']

Suffixed Parameters

Optional

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

Zero or more

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

One or more

Parameters can be suffixed with a plus sign (+) to denote a one or more parameters match. The prefixed path delimiter is included in the 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']

Custom Match Parameters

All parameters can be provided a custom matching regexp and override the default. Please note: Backslashes need to be escaped in strings.

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

re.exec('/123')
//=> ['/123', '123']

re.exec('/abc')
//=> null

Unnamed Parameters

It is possible to write an unnamed parameter that is only 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']

Asterisk

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']

Parse

The parse function is exposed via pathToRegexp.parse. This will yield 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 strings.

Compile ("Reverse" Path-To-RegExp)

Path-To-RegExp exposes a compile function for transforming an express path into valid path. Confusing enough? This example will straighten everything out for you.

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 any invalid input. It will execute 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.

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*

Live Demo

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

License

MIT