regexparam 
A tiny (394B) utility that converts route patterns into RegExp. Limited alternative to
path-to-regexp🙇
With regexparam, you may turn a pathing string (eg, /users/:id) into a regular expression.
An object with shape of { keys, pattern } is returned, where pattern is the RegExp and keys is an array of your parameter name(s) in the order that they appeared.
Unlike path-to-regexp, this module does not create a keys dictionary, nor mutate an existing variable. Also, this only ships a parser, which only accept strings. Similarly, and most importantly, regexparam only handles basic pathing operators:
- Static (
/foo,/foo/bar) - Parameter (
/:title,/books/:title,/books/:genre/:title) - Parameter w/ Suffix (
/movies/:title.mp4,/movies/:title.(mp4|mov)) - Optional Parameters (
/:title?,/books/:title?,/books/:genre/:title?) - Wildcards (
*,/books/*,/books/:genre/*)
This module exposes three module definitions:
- CommonJS:
dist/index.js - ESModule:
dist/index.mjs - UMD:
dist/index.min.js
Install
$ npm install --save regexparam
Usage
import { parse, inject } from 'regexparam';
// Example param-assignment
function exec(path, result) {
let i=0, out={};
let matches = result.pattern.exec(path);
while (i < result.keys.length) {
out[ result.keys[i] ] = matches[++i] || null;
}
return out;
}
// Parameter, with Optional Parameter
// ---
let foo = parse('/books/:genre/:title?')
// foo.pattern => /^\/books\/([^\/]+?)(?:\/([^\/]+?))?\/?$/i
// foo.keys => ['genre', 'title']
foo.pattern.test('/books/horror'); //=> true
foo.pattern.test('/books/horror/goosebumps'); //=> true
exec('/books/horror', foo);
//=> { genre: 'horror', title: null }
exec('/books/horror/goosebumps', foo);
//=> { genre: 'horror', title: 'goosebumps' }
// Parameter, with suffix
// ---
let bar = parse('/movies/:title.(mp4|mov)');
// bar.pattern => /^\/movies\/([^\/]+?)\.(mp4|mov)\/?$/i
// bar.keys => ['title']
bar.pattern.test('/movies/narnia'); //=> false
bar.pattern.test('/movies/narnia.mp3'); //=> false
bar.pattern.test('/movies/narnia.mp4'); //=> true
exec('/movies/narnia.mp4', bar);
//=> { title: 'narnia' }
// Wildcard
// ---
let baz = parse('users/*');
// baz.pattern => /^\/users\/(.*)\/?$/i
// baz.keys => ['wild']
baz.pattern.test('/users'); //=> false
baz.pattern.test('/users/lukeed'); //=> true
exec('/users/lukeed/repos/new', baz);
//=> { wild: 'lukeed/repos/new' }
// Injecting
// ---
inject('/users/:id', {
id: 'lukeed'
}); //=> '/users/lukeed'
inject('/movies/:title.mp4', {
title: 'narnia'
}); //=> '/movies/narnia.mp4'
inject('/:foo/:bar?/:baz?', {
foo: 'aaa'
}); //=> '/aaa'
inject('/:foo/:bar?/:baz?', {
foo: 'aaa',
baz: 'ccc'
}); //=> '/aaa/ccc'
inject('/posts/:slug/*', {
slug: 'hello',
}); //=> '/posts/hello'
inject('/posts/:slug/*', {
slug: 'hello',
wild: 'x/y/z',
}); //=> '/posts/hello/x/y/z'
// Missing non-optional value
// ~> keeps the pattern in output
inject('/hello/:world', {
abc: 123
}); //=> '/hello/:world'Important: When matching/testing against a generated RegExp, your path must begin with a leading slash (
"/")!
Regular Expressions
For fine-tuned control, you may pass a RegExp value directly to regexparam as its only parameter.
In these situations, regexparam does not parse nor manipulate your pattern in any way! Because of this, regexparam has no "insight" on your route, and instead trusts your input fully. In code, this means that the return value's keys is always equal to false and the pattern is identical to your input value.
This also means that you must manage and parse your own keys~!
You may use named capture groups or traverse the matched segments manually the "old-fashioned" way:
Important: Please check your target browsers' and target Node.js runtimes' support!
// Named capture group
const named = regexparam.parse(/^\/posts[/](?<year>[0-9]{4})[/](?<month>[0-9]{2})[/](?<title>[^\/]+)/i);
const { groups } = named.pattern.exec('/posts/2019/05/hello-world');
console.log(groups);
//=> { year: '2019', month: '05', title: 'hello-world' }
// Widely supported / "Old-fashioned"
const named = regexparam.parse(/^\/posts[/]([0-9]{4})[/]([0-9]{2})[/]([^\/]+)/i);
const [url, year, month, title] = named.pattern.exec('/posts/2019/05/hello-world');
console.log(year, month, title);
//=> 2019 05 hello-worldAPI
regexparam.parse(input: RegExp)
regexparam.parse(input: string, loose?: boolean)
Returns: Object
Parse a route pattern into an equivalent RegExp pattern. Also collects the names of pattern's parameters as a keys array. An input that's already a RegExp is kept as is, and regexparam makes no additional insights.
Returns a { keys, pattern } object, where pattern is always a RegExp instance and keys is either false or a list of extracted parameter names.
Important: The
keyswill always befalsewheninputis a RegExp and it will always be an Array wheninputis a string.
input
Type: string or RegExp
When input is a string, it's treated as a route pattern and an equivalent RegExp is generated.
Note: It does not matter if
inputstrings begin with a/— it will be added if missing.
When input is a RegExp, it will be used as is – no modifications will be made.
loose
Type: boolean
Default: false
Should the RegExp match URLs that are longer than the str pattern itself?
By default, the generated RegExp will test that the URL begins and ends with the pattern.
Important: When
inputis a RegExp, thelooseargument is ignored!
const { parse } = require('regexparam');
parse('/users').pattern.test('/users/lukeed'); //=> false
parse('/users', true).pattern.test('/users/lukeed'); //=> true
parse('/users/:name').pattern.test('/users/lukeed/repos'); //=> false
parse('/users/:name', true).pattern.test('/users/lukeed/repos'); //=> trueregexparam.inject(pattern: string, values: object)
Returns: string
Returns a new string by replacing the pattern segments/parameters with their matching values.
Important: Named segments (eg,
/:name) that do not have avaluesmatch will be kept in the output. This is true except for optional segments (eg,/:name?) and wildcard segments (eg,/*).
pattern
Type: string
The route pattern that to receive injections.
values
Type: Record<string, string>
The values to be injected. The keys within values must match the pattern's segments in order to be replaced.
Note: To replace a wildcard segment (eg,
/*), define avalues.wildkey.
Deno
As of version 1.3.0, you may use regexparam with Deno. These options are all valid:
// The official Deno registry:
import regexparam from 'https://deno.land/x/regexparam/src/index.js';
// Third-party CDNs with ESM support:
import regexparam from 'https://cdn.skypack.dev/regexparam';
import regexparam from 'https://esm.sh/regexparam';Note: All registries support versioned URLs, if desired.
The above examples always resolve to the latest published version.
Related
- trouter - A server-side HTTP router that extends from this module.
- matchit - Similar (650B) library, but relies on String comparison instead of
RegExps.
License
MIT © Luke Edwards