Path-to-RegExp

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

Installation

npm install path-to-regexp --save

Usage

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

Parameters

Parameters match arbitrary strings in a path by matching up to the end of the segment, or up to any proceeding tokens. They are defined by prefixing a colon to the parameter name (:foo). Parameter names can use any valid JavaScript identifier, or be double quoted to use other characters (:"param-name").

const fn = match("/:foo/:bar");

fn("/test/route");
//=> { path: '/test/route', params: { foo: 'test', bar: 'route' } }

Wildcard

Wildcard parameters match one or more characters across multiple segments. They are defined the same way as regular parameters, but are prefixed with an asterisk (*foo).

const fn = match("/*splat");

fn("/bar/baz");
//=> { path: '/bar/baz', params: { splat: [ 'bar', 'baz' ] } }

Optional

Braces can be used to define parts of the path that are optional.

const fn = match("/users{/:id}/delete");

fn("/users/delete");
//=> { path: '/users/delete', params: {} }

fn("/users/123/delete");
//=> { path: '/users/123/delete', params: { id: '123' } }

Match

The match function returns a function for matching strings against a path:

• path String or array of strings.
• options (optional) (Extends pathToRegexp options)
  • decode Function for decoding strings to params, or false to disable all processing. (default: decodeURIComponent)

const fn = match("/foo/:bar");

Please note: path-to-regexp is intended for ordered data (e.g. paths, hosts). It can not handle arbitrarily ordered data (e.g. query strings, URL fragments, JSON, etc).

PathToRegexp

The pathToRegexp function returns a regular expression for matching strings against paths. It

• path String or array of strings.
• options (optional) (See parse for more options)
  • sensitive Regexp will be case sensitive. (default: false)
  • end Validate the match reaches the end of the string. (default: true)
  • delimiter The default delimiter for segments, e.g. [^/] for :named parameters. (default: '/')
  • trailing Allows optional trailing delimiter to match. (default: true)

const { regexp, keys } = pathToRegexp("/foo/:bar");

Compile ("Reverse" Path-To-RegExp)

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

• path A string.
• options (See parse for more options)
  • delimiter The default delimiter for segments, e.g. [^/] for :named parameters. (default: '/')
  • encode Function for encoding input strings for output into the path, or false to disable entirely. (default: encodeURIComponent)

const toPath = compile("/user/:id");

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

const toPathRepeated = compile("/*segment");

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

// When disabling `encode`, you need to make sure inputs are encoded correctly. No arrays are accepted.
const toPathRaw = compile("/user/:id", { encode: false });

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

Stringify

Transform TokenData (a sequence of tokens) back into a Path-to-RegExp string.

• data A TokenData instance

const data = new TokenData([
  { type: "text", value: "/" },
  { type: "param", name: "foo" },
]);

const path = stringify(data); //=> "/:foo"

Developers

• If you are rewriting paths with match and compile, consider using encode: false and decode: false to keep raw paths passed around.
• To ensure matches work on paths containing characters usually encoded, such as emoji, consider using encodeurl for encodePath.

Parse

The parse function accepts a string and returns TokenData, the set of tokens and other metadata parsed from the input string. TokenData is can used with match and compile.

• path A string.
• options (optional)
  • encodePath A function for encoding input strings. (default: x => x, recommended: encodeurl)

Tokens

TokenData is a sequence of tokens, currently of types text, parameter, wildcard, or group.

Custom path

In some applications, you may not be able to use the path-to-regexp syntax, but still want to use this library for match and compile. For example:

import { TokenData, match } from "path-to-regexp";

const tokens = [
  { type: "text", value: "/" },
  { type: "parameter", name: "foo" },
];
const path = new TokenData(tokens);
const fn = match(path);

fn("/test"); //=> { path: '/test', index: 0, params: { foo: 'test' } }

Errors

An effort has been made to ensure ambiguous paths from previous releases throw an error. This means you might be seeing an error when things worked before.

Unexpected ? or +

In past releases, ?, *, and + were used to denote optional or repeating parameters. As an alternative, try these:

• For optional (?), use an empty segment in a group such as /:file{.:ext}.
• For repeating (+), only wildcard matching is supported, such as /*path.
• For optional repeating (*), use a group and a wildcard parameter such as /files{/*path}.

Unexpected (, ), [, ], etc.

Previous versions of Path-to-RegExp used these for RegExp features. This version no longer supports them so they've been reserved to avoid ambiguity. To use these characters literally, escape them with a backslash, e.g. "\\(".

Missing parameter name

Parameter names must be provided after : or *, and they must be a valid JavaScript identifier. If you want an parameter name that isn't a JavaScript identifier, such as starting with a number, you can wrap the name in quotes like :"my-name".

Unterminated quote

Parameter names can be wrapped in double quote characters, and this error means you forgot to close the quote character.

Express <= 4.x

Path-To-RegExp breaks compatibility with Express <= 4.x in the following ways:

• The wildcard * must have a name, matching the behavior of parameters :.
• The optional character ? is no longer supported, use braces instead: /:file{.:ext}.
• Regexp characters are not supported.
• Some characters have been reserved to avoid confusion during upgrade (()[]?+!).
• Parameter names now support valid JavaScript identifiers, or quoted like :"this".

License

MIT