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 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: '[^\\/]+?' }]

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

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']

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']

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']

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']

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

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']

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.

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') var result = toPath({ id: 123 }) console.log(result) //=> "/user/123"

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.

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 in a few ways:

• RegExp special characters can now be used in the regular path. E.g. /user/(\\d+)
• All RegExp special characters can now be used inside the custom match. E.g. /:user(.*)
• No more support for asterisk matching - use an explicit parameter instead. E.g. /(.*)
• Parameters can have suffixes that augment meaning - *, + and ?. E.g. /:user*
• Strings aren't interpreted as literal regexp strings - no more non-capturing groups, lookaheads, lookbehinds or nested matching groups (but you can still pass a regexp manually)

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

MIT