238 lines
7.9 KiB
Markdown
238 lines
7.9 KiB
Markdown
# regexparam [](https://github.com/lukeed/regexparam/actions/workflows/ci.yml)
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> A tiny (394B) utility that converts route patterns into RegExp. Limited alternative to [`path-to-regexp`](https://github.com/pillarjs/path-to-regexp) 🙇
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With `regexparam`, you may turn a pathing string (eg, `/users/:id`) into a regular expression.
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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.
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Unlike [`path-to-regexp`](https://github.com/pillarjs/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:
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* Static (`/foo`, `/foo/bar`)
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* Parameter (`/:title`, `/books/:title`, `/books/:genre/:title`)
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* Parameter w/ Suffix (`/movies/:title.mp4`, `/movies/:title.(mp4|mov)`)
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* Optional Parameters (`/:title?`, `/books/:title?`, `/books/:genre/:title?`)
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* Wildcards (`*`, `/books/*`, `/books/:genre/*`)
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This module exposes three module definitions:
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* **CommonJS**: [`dist/index.js`](https://unpkg.com/regexparam/dist/index.js)
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* **ESModule**: [`dist/index.mjs`](https://unpkg.com/regexparam/dist/index.mjs)
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* **UMD**: [`dist/index.min.js`](https://unpkg.com/regexparam/dist/index.min.js)
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## Install
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```
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$ npm install --save regexparam
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```
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## Usage
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```js
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import { parse, inject } from 'regexparam';
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// Example param-assignment
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function exec(path, result) {
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let i=0, out={};
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let matches = result.pattern.exec(path);
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while (i < result.keys.length) {
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out[ result.keys[i] ] = matches[++i] || null;
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}
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return out;
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}
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// Parameter, with Optional Parameter
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// ---
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let foo = parse('/books/:genre/:title?')
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// foo.pattern => /^\/books\/([^\/]+?)(?:\/([^\/]+?))?\/?$/i
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// foo.keys => ['genre', 'title']
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foo.pattern.test('/books/horror'); //=> true
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foo.pattern.test('/books/horror/goosebumps'); //=> true
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exec('/books/horror', foo);
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//=> { genre: 'horror', title: null }
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exec('/books/horror/goosebumps', foo);
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//=> { genre: 'horror', title: 'goosebumps' }
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// Parameter, with suffix
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// ---
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let bar = parse('/movies/:title.(mp4|mov)');
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// bar.pattern => /^\/movies\/([^\/]+?)\.(mp4|mov)\/?$/i
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// bar.keys => ['title']
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bar.pattern.test('/movies/narnia'); //=> false
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bar.pattern.test('/movies/narnia.mp3'); //=> false
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bar.pattern.test('/movies/narnia.mp4'); //=> true
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exec('/movies/narnia.mp4', bar);
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//=> { title: 'narnia' }
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// Wildcard
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// ---
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let baz = parse('users/*');
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// baz.pattern => /^\/users\/(.*)\/?$/i
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// baz.keys => ['wild']
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baz.pattern.test('/users'); //=> false
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baz.pattern.test('/users/lukeed'); //=> true
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exec('/users/lukeed/repos/new', baz);
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//=> { wild: 'lukeed/repos/new' }
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// Injecting
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// ---
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inject('/users/:id', {
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id: 'lukeed'
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}); //=> '/users/lukeed'
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inject('/movies/:title.mp4', {
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title: 'narnia'
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}); //=> '/movies/narnia.mp4'
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inject('/:foo/:bar?/:baz?', {
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foo: 'aaa'
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}); //=> '/aaa'
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inject('/:foo/:bar?/:baz?', {
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foo: 'aaa',
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baz: 'ccc'
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}); //=> '/aaa/ccc'
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inject('/posts/:slug/*', {
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slug: 'hello',
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}); //=> '/posts/hello'
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inject('/posts/:slug/*', {
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slug: 'hello',
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wild: 'x/y/z',
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}); //=> '/posts/hello/x/y/z'
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// Missing non-optional value
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// ~> keeps the pattern in output
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inject('/hello/:world', {
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abc: 123
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}); //=> '/hello/:world'
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```
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> **Important:** When matching/testing against a generated RegExp, your path **must** begin with a leading slash (`"/"`)!
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## Regular Expressions
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For fine-tuned control, you may pass a `RegExp` value directly to `regexparam` as its only parameter.
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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.
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This also means that you must manage and parse your own `keys`~!<br>
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You may use [named capture groups](https://javascript.info/regexp-groups#named-groups) or traverse the matched segments manually the "old-fashioned" way:
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> **Important:** Please check your target browsers' and target [Node.js runtimes' support](https://node.green/#ES2018-features--RegExp-named-capture-groups)!
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```js
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// Named capture group
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const named = regexparam.parse(/^\/posts[/](?<year>[0-9]{4})[/](?<month>[0-9]{2})[/](?<title>[^\/]+)/i);
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const { groups } = named.pattern.exec('/posts/2019/05/hello-world');
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console.log(groups);
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//=> { year: '2019', month: '05', title: 'hello-world' }
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// Widely supported / "Old-fashioned"
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const named = regexparam.parse(/^\/posts[/]([0-9]{4})[/]([0-9]{2})[/]([^\/]+)/i);
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const [url, year, month, title] = named.pattern.exec('/posts/2019/05/hello-world');
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console.log(year, month, title);
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//=> 2019 05 hello-world
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```
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## API
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### regexparam.parse(input: RegExp)
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### regexparam.parse(input: string, loose?: boolean)
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Returns: `Object`
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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.
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Returns a `{ keys, pattern }` object, where `pattern` is always a `RegExp` instance and `keys` is either `false` or a list of extracted parameter names.
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> **Important:** The `keys` will _always_ be `false` when `input` is a RegExp and it will _always_ be an Array when `input` is a string.
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#### input
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Type: `string` or `RegExp`
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When `input` is a string, it's treated as a route pattern and an equivalent RegExp is generated.
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> **Note:** It does not matter if `input` strings begin with a `/` — it will be added if missing.
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When `input` is a RegExp, it will be used **as is** – no modifications will be made.
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#### loose
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Type: `boolean`<br>
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Default: `false`
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Should the `RegExp` match URLs that are longer than the [`str`](#str) pattern itself?<br>
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By default, the generated `RegExp` will test that the URL begins and _ends with_ the pattern.
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> **Important:** When `input` is a RegExp, the `loose` argument is ignored!
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```js
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const { parse } = require('regexparam');
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parse('/users').pattern.test('/users/lukeed'); //=> false
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parse('/users', true).pattern.test('/users/lukeed'); //=> true
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parse('/users/:name').pattern.test('/users/lukeed/repos'); //=> false
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parse('/users/:name', true).pattern.test('/users/lukeed/repos'); //=> true
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```
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### regexparam.inject(pattern: string, values: object)
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Returns: `string`
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Returns a new string by replacing the `pattern` segments/parameters with their matching values.
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> **Important:** Named segments (eg, `/:name`) that _do not_ have a `values` match will be kept in the output. This is true _except for_ optional segments (eg, `/:name?`) and wildcard segments (eg, `/*`).
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#### pattern
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Type: `string`
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The route pattern that to receive injections.
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#### values
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Type: `Record<string, string>`
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The values to be injected. The keys within `values` must match the `pattern`'s segments in order to be replaced.
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> **Note:** To replace a wildcard segment (eg, `/*`), define a `values.wild` key.
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## Deno
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As of version `1.3.0`, you may use `regexparam` with Deno. These options are all valid:
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```ts
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// The official Deno registry:
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import regexparam from 'https://deno.land/x/regexparam/src/index.js';
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// Third-party CDNs with ESM support:
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import regexparam from 'https://cdn.skypack.dev/regexparam';
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import regexparam from 'https://esm.sh/regexparam';
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```
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> **Note:** All registries support versioned URLs, if desired. <br>The above examples always resolve to the latest published version.
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## Related
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- [trouter](https://github.com/lukeed/trouter) - A server-side HTTP router that extends from this module.
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- [matchit](https://github.com/lukeed/matchit) - Similar (650B) library, but relies on String comparison instead of `RegExp`s.
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## License
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MIT © [Luke Edwards](https://lukeed.com)
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