pillarjs/path-to-regexp


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

License: MIT

Language: TypeScript

Keywords: expressjs, nodejs, path-to-regexp, router


Path-to-RegExp

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

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Installation

npm install path-to-regexp --save

Usage

const { pathToRegexp, match, parse, compile } = require("path-to-regexp");

// pathToRegexp(path, keys?, options?)
// match(path)
// parse(path)
// compile(path)
  • path A string, array of strings, or a regular expression.
  • keys An array to populate 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)
    • delimiter The default delimiter for segments. (default: '/')
    • endsWith Optional character, or list of characters, to treat as "end" characters.
    • whitelist List of characters to consider delimiters when parsing. (default: undefined, any character)
    • encode A function to encode strings before inserting into RegExp. (default: x => x)
const keys = [];
const regexp = pathToRegexp("/foo/:bar", keys);
// regexp = /^\/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 can not handle arbitrarily ordered data (e.g. query strings, URL fragments, JSON, etc).

Parameters

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 next prefix (e.g. [^/]+).

const regexp = pathToRegexp("/:foo/:bar");
// keys = [{ name: 'foo', prefix: '/', ... }, { name: 'bar', prefix: '/', ... }]

regexp.exec("/test/route");
//=> [ '/test/route', 'test', 'route', index: 0, input: '/test/route', groups: undefined ]

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

Parameter Modifiers

Optional

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

const regexp = pathToRegexp("/:foo/:bar?");
// keys = [{ name: 'foo', ... }, { name: 'bar', delimiter: '/', optional: true, repeat: false }]

regexp.exec("/test");
//=> [ '/test', 'test', undefined, index: 0, input: '/test', groups: undefined ]

regexp.exec("/test/route");
//=> [ '/test/route', 'test', 'route', index: 0, input: '/test/route', groups: undefined ]

Tip: The prefix is also optional, escape the prefix \/ to make it required.

Zero or more

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

const regexp = pathToRegexp("/:foo*");
// keys = [{ name: 'foo', delimiter: '/', optional: true, repeat: true }]

regexp.exec("/");
//=> [ '/', undefined, index: 0, input: '/', groups: undefined ]

regexp.exec("/bar/baz");
//=> [ '/bar/baz', 'bar/baz', index: 0, input: '/bar/baz', groups: undefined ]
One or more

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

const regexp = pathToRegexp("/:foo+");
// keys = [{ name: 'foo', delimiter: '/', optional: false, repeat: true }]

regexp.exec("/");
//=> null

regexp.exec("/bar/baz");
//=> [ '/bar/baz','bar/baz', index: 0, input: '/bar/baz', groups: undefined ]

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.

const regexp = pathToRegexp("/:foo/(.*)");
// keys = [{ name: 'foo', ... }, { name: 0, ... }]

regexp.exec("/test/route");
//=> [ '/test/route', 'test', 'route', index: 0, input: '/test/route', groups: undefined ]

Custom Matching Parameters

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

const regexpNumbers = pathToRegexp("/icon-:foo(\\d+).png");
// keys = [{ name: 'foo', ... }]

regexpNumbers.exec("/icon-123.png");
//=> ['/icon-123.png', '123']

regexpNumbers.exec("/icon-abc.png");
//=> null

const regexpWord = pathToRegexp("/(user|u)");
// keys = [{ name: 0, ... }]

regexpWord.exec("/u");
//=> ['/u', 'u']

regexpWord.exec("/users");
//=> null

Tip: Backslashes need to be escaped with another backslash in JavaScript strings.

Match

The match function will return a function for transforming paths into parameters:

// Make sure you consistently `decode` segments.
const match = match("/user/:id", { decode: decodeURIComponent });

match("/user/123"); //=> { path: '/user/123', index: 0, params: { id: '123' } }
match("/invalid"); //=> false
match("/user/caf%C3%A9"); //=> { path: '/user/caf%C3%A9', index: 0, params: { id: 'café' } }

Normalize Pathname

You should make sure variations of the same path to match your input path. Here's one possible solution:

/**
 * Normalize a pathname for matching, replaces multiple slashes with a single
 * slash and normalizes unicode characters to "NFC". When using this method,
 * `decode` should be an identity function so you don't decode strings twice.
 */
function normalizePathname(pathname: string) {
  return (
    decodeURI(pathname)
      // Replaces repeated slashes in the URL.
      .replace(/\/+/g, "/")
      // Reference: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/normalize
      // Note: Missing native IE support, may want to skip this step.
      .normalize()
  );
}

const re = pathToRegexp("/caf\u00E9");
const input = encodeURI("/cafe\u0301");

re.test(input); //=> false
re.test(normalizePathname(input)); //=> true

Note: URL automatically encodes pathnames for you, which would result in a consistent match if you use encodeURI in pathToRegexp options.

Parse

The parse function will return a list of strings and keys from a path string:

const tokens = 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)

The compile function will return a function for transforming parameters into a valid path:

// Make sure you encode your path segments consistently.
const toPath = compile("/user/:id", { encode: encodeURIComponent });

toPath({ id: 123 }); //=> "/user/123"
toPath({ id: "café" }); //=> "/user/caf%C3%A9"
toPath({ id: "/" }); //=> "/user/%2F"

toPath({ id: ":/" }); //=> "/user/%3A%2F"

// Without `encode`, you need to make sure inputs are encoded correctly.
const toPathRaw = compile("/user/:id");

toPathRaw({ id: "%3A%2F" }); //=> "/user/%3A%2F"
toPathRaw({ id: ":/" }, { validate: false }); //=> "/user/:/"

const toPathRepeated = compile("/:segment+");

toPathRepeated({ segment: "foo" }); //=> "/foo"
toPathRepeated({ segment: ["a", "b", "c"] }); //=> "/a/b/c"

const toPathRegexp = compile("/user/:id(\\d+)");

toPathRegexp({ id: 123 }); //=> "/user/123"
toPathRegexp({ id: "123" }); //=> "/user/123"
toPathRegexp({ id: "abc" }); //=> Throws `TypeError`.
toPathRegexp({ id: "abc" }, { validate: false }); //=> "/user/abc"

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.

  • tokensToRegexp(tokens, keys?, options?) Transform an array of tokens into a matching regular expression.
  • 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 unnamed index)
  • prefix The prefix character for the segment (e.g. /)
  • delimiter The delimiter for the segment (same as prefix or default delimiter)
  • optional Indicates the token is optional (boolean)
  • repeat Indicates the token is repeated (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 supported RegExp special characters regardless of position - this is considered a bug
  • Parameters have suffixes that augment meaning - *, + and ?. E.g. /:user*
  • No wildcard asterisk (*) - use parameters instead ((.*) or :splat*)

Live Demo

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

License

MIT

Project Statistics

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Repository Size 518 KB
Stars 4,842
Forks 243
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Dependencies 776
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Recent Tags See all

v6.1.0 November 20, 2019
v6.0.0 November 20, 2019
v5.0.0 November 12, 2019
v4.0.5 November 12, 2019
v4.0.4 November 12, 2019
v4.0.3 November 12, 2019
v4.0.2 November 12, 2019
v4.0.1 November 12, 2019
v4.0.0 November 12, 2019
v3.2.0 November 11, 2019
v1.8.0 November 11, 2019
v3.1.0 August 31, 2019
v3.0.0 January 14, 2019
v2.4.0 August 26, 2018
v2.3.0 August 20, 2018

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