@keenmate/svelte-spa-router
v1.0.8
Published
Router for SPAs using Svelte 4
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Readme
svelte-spa-router
This is a fork of ItalyPaleAle/svelte-spa-router. This fork adds option to not use hash-based routing and instead leverage
History
'spushState
/replaceState
No hash routing
To configure library to not use hash routing, you need to set config before App initializes (in main.js/ts
):
Config preparation
import {HashRoutingEnabled, BasePath} from "@keenmate/svelte-spa-router"
HashRoutingEnabled.set(false)
BasePath.set(import.meta.env.BASE_URL)
Usage
The trick is in a mandatory use of use:link
on HTML links to augment these links to call pushState
/replaceState
instead of actual navigation
As a bonus, it automatically prepends BasePath
value to these links if it is not already present
<a href="/home" use:link>
Link to home
</a>
<a href="/about" use:link>
Link to about
</a>
Original README
This module is a router for Svelte 3 and 4 applications, specifically optimized for Single Page Applications (SPA).
Main features:
- Leverages hash-based routing, which is optimal for SPAs and doesn't require any server-side processing
- Insanely simple to use, and has a minimal footprint
- Uses the tiny regexparam for parsing routes, with support for parameters (e.g.
/book/:id?
) and more
This module is released under MIT license.
Video
"So you want to pick a router?" talk by @ItalyPaleAle at Svelte Summit
2020. Includes an explanation of the two kinds of routers and a demo of svelte-spa-router.
(Click on the cover image to play the video on YouTube)
Hash-based routing
With hash-based routing, navigation is possible thanks to storing the current view in the part of the URL after #
,
called "hash" or "fragment".
For example, if your SPA is in a static file called index.html
, your URLs for navigating within the app look something
like index.html#/profile
, index.html#/book/42
, etc. (The index.html
part can usually be omitted for the index
file, so you can just create URLs that look like http://example.com/#/profile
).
When I created this component, other routers for Svelte 3+ implemented navigation using the HTML5 history API. While
those URLs look nicer (e.g. you can actually navigate to http://example.com/profile
), they are not ideal for static
Single Page Applications. In order for users to be able to share links or even just refresh the page, you are required
to have a server on the backend processing the request, and building fully-static apps is much harder as a consequence.
Hash-based routing is simpler, works well even without a server, and it's generally better suited for static SPAs, especially when SEO isn't a concern, as is the case when the app requires authentication. Many popular apps use hash-based routing, including GMail!
Sample code
Check out the code in the examples folder for some usage examples.
To run the samples, clone the repository, install the dependencies, then build each sample using Rollup:
git clone https://github.com/ItalyPaleAle/svelte-spa-router
cd svelte-spa-router
npm install
# Navigate to a sample
cd examples/…
# For example
cd examples/basic-routing
# Build and run (in the folder of a sample)
npx rollup -c
npx serve -n -l 5050 dist
The sample will be running at http://localhost:5050
Starter template
You can find a starter template with Svelte 4 and svelte-spa-router at italypaleale/svelte-spa-router-template.
To use the template:
npx degit italypaleale/svelte-spa-router-template svelte-app
cd svelte-app
More information can be found on the template's repo.
Using svelte-spa-router
You can include the router in any project using Svelte 3 or 4.
Install from NPM
To add svelte-spa-router to your project:
npm install svelte-spa-router
Supported browsers
svelte-spa-router aims to support modern browsers, including recent versions of:
- Chrome
- Edge ("traditional" and Chromium-based)
- Firefox
- Safari
Support for Internet Explorer is not a goal for this project. Some users have reportedly been able to use svelte-spa-router with IE11 after transpilation (e.g. with Babel), but this is not guaranteed.
Define your routes
Each route is a normal Svelte component, with the markup, scripts, bindings, etc. Any Svelte component can be a route.
The route definition is just a JavaScript dictionary (object) where the key is a string with the path (including parameters, etc), and the value is the route object.
For example:
import Home from './routes/Home.svelte'
import Author from './routes/Author.svelte'
import Book from './routes/Book.svelte'
import NotFound from './routes/NotFound.svelte'
const routes = {
// Exact path
'/': Home,
// Using named parameters, with last being optional
'/author/:first/:last?': Author,
// Wildcard parameter
'/book/*': Book,
// Catch-all
// This is optional, but if present it must be the last
'*': NotFound,
}
Routes must begin with /
(or *
for the catch-all route).
Alternatively, you can also define your routes using custom regular expressions, as explained below.
Note that the order matters! When your users navigate inside the app, the first matching path will determine which route to load. It's important that you leave any "catch-all" route (e.g. a "Page not found" one) at the end.
Include the router view
To display the router, in a Svelte component (usually App.svelte
), first import the router component:
import Router from 'svelte-spa-router'
Then, display the router anywhere you'd like by placing the component in the markup. For example:
<body>
<Router {routes}/>
</body>
The routes
prop is the dictionary defined above.
That's it! You already have all that you need for a fully-functional routing experience.
Dynamically-imported components and code-splitting
Starting with version 3.0, svelte-spa-router supports dynamically-imported components (via the import()
construct).
The advantage of using dynamic imports is that, if your bundler supports that, you can enable code-splitting and reduce
the size of the bundle you send to your users. This has been tested with bundlers including Rollup and Webpack.
To use dynamically-imported components, you need to leverage the wrap
method (which can be used for a variety of
actions, as per the docs on route wrapping). First, import the wrap
method:
import {wrap} from 'svelte-spa-router/wrap'
Then, in your route definition, wrap your routes using the wrap
method, passing a function that returns the
dynamically-imported component to the asyncComponent
property:
wrap({
asyncComponent: () => import('./Foo.svelte')
})
Note: the value of
asyncComponent
must be the definition of a function returning a dynamically-imported component, such asasyncComponent: () => import('./Foo.svelte')
.
Do not useasyncComponent: import('./Foo.svelte')
, which is a function invocation instead.
For example, to make the Author and Book routes from the first example dynamically-imported, we'd update the code to:
// Import the wrap method
import {wrap} from 'svelte-spa-router/wrap'
// Note that Author and Book are not imported here anymore, so they can be imported at runtime
import Home from './routes/Home.svelte'
import NotFound from './routes/NotFound.svelte'
const routes = {
'/': Home,
// Wrapping the Author component
'/author/:first/:last?': wrap({
asyncComponent: () => import('./routes/Author.svelte')
}),
// Wrapping the Book component
'/book/*': wrap({
asyncComponent: () => import('./routes/Book.svelte')
}),
// Catch-all route last
'*': NotFound,
}
The wrap
method accepts an object with multiple properties and enables other features, including: setting a "loading"
component that is shown while a dynamically-imported component is being requested, adding pre-conditions (route guards),
passing static props, and adding custom user data.
You can learn more about all the features of wrap
in the documentation
for route wrapping.
Navigating between pages
You can navigate between pages with normal anchor (<a>
) tags. For example:
<a href="#/book/123">Thus Spoke Zarathustra</a>
The use:link
action
Rather than having to type #
before each link, you can also use the use:link
action:
<script>
import {link} from 'svelte-spa-router'
</script>
<a href="/book/321" use:link>The Little Prince</a>
The use:link
action accepts an optional parameter opts
, which can be one of:
- A dictionary
{href: '/foo', disabled: false}
where both keys are optional:- If you set a value for
href
, your link will be updated to point to that address, reactively (this will always take precedence overhref
attributes, if present) - Setting
disabled: true
disables the link, so clicking on that would have no effect
- If you set a value for
- A string with a destination (e.g.
/foo
), which is a shorthand to setting{href: '/foo'}
.
For example:
<script>
import {link} from 'svelte-spa-router'
let myLink = "/book/456"
</script>
<!-- Note the {{...}} notation because we're passing an object as parameter for a Svelte action -->
<a use:link={{href: myLink, disabled: false}}>The Biggest Princess</a>
The above is equivalent to:
<script>
import {link} from 'svelte-spa-router'
let myLink = "/book/456"
</script>
<a use:link={myLink}>The Biggest Princess</a>
Changing the value of myLink
will reactively update the link's href
attribute.
Navigating programmatically
You can navigate between pages programmatically too:
import {push, pop, replace} from 'svelte-spa-router'
// The push(url) method navigates to another page, just like clicking on a link
push('/book/42')
// The pop() method is equivalent to hitting the back button in the browser
pop()
// The replace(url) method navigates to a new page, but without adding a new entry in the browser's history stack
// So, clicking on the back button in the browser would not lead to the page users were visiting before the call to replace()
replace('/book/3')
These methods can be used inside Svelte markup too, for example:
<button on:click={() => push('/page')}>Go somewhere</button>
The push
, pop
and replace
methods perform navigation actions only in the next iteration ("tick") of the JavaScript
event loop. This makes it safe to use them also inside onMount
callbacks within Svelte components.
These functions return a Promise that resolves with no value once the navigation has been triggered (in the next tick of the event loop); however, please note that this will likely be before the new page has rendered.
Parameters from routes
svelte-spa-router uses regexparam to parse routes, so you can add optional parameters to the route. Basic syntax is:
/path
matches/path
exactly (and only that)/path/:id
matches/path/
followed by any string, which is a named argumentid
/path/:id/:version?
allows for an optional second named argumentversion
/path/*
matches/path/
followed by anything, using a non-named argument
Please refer to the documentation of regexparam for more details.
If your route contains any parameter, they will be made available to your component inside the params
dictionary.
For example, for a route /name/:first/:last?
, you can create this Svelte component:
<p>Your name is: <b>{params.first}</b> <b>{#if params.last}{params.last}{/if}</b></p>
<script>
// You need to define the component prop "params"
export let params = {}
</script>
Non-named arguments are returned as params.wild
.
Getting the current page
You can get the current page from the $location
readable store. This is a Svelte store, so it can be used reactively
too.
<script>
import {location} from 'svelte-spa-router'
</script>
<p>The current page is: {$location}</p>
Querystring parameters
You can also extract "querystring" parameters from the hash of the page. This isn't the real querystring, as it's
located after the #
character in the URL, but it can be used in a similar way. For example:
#/books?show=authors,titles&order=1
.
When svelte-spa-router finds a "querystring" in the hash, it separates that from the location and returns it as a string
in the Svelte store $querystring
. For example:
<script>
import {location, querystring} from 'svelte-spa-router'
</script>
<p>The current page is: {$location}</p>
<p>The querystring is: {$querystring}</p>
With the example above, this would print:
The current page is: /books
The querystring is: show=authors,titles&order=1
It's important to note that, to keep this component lightweight, svelte-spa-router does not parse the "querystring".
If you want to parse the value of $querystring
, you can
use URLSearchParams available in all modern
browsers, or third-party modules such as qs.
Highlight active links
svelte-spa-router has built-in support for automatically marking links as "active", with the use:active
action.
For example, you can use the code below to add the CSS class active
to links that are active:
<script>
import {link} from 'svelte-spa-router'
import active from 'svelte-spa-router/active'
</script>
<style>
/* Style for "active" links; need to mark this :global because the router adds the class directly */
:global(a.active) {
color: red;
}
</style>
<a href="/hello/user" use:link use:active={{path: '/hello/*', className: 'active', inactiveClassName: 'inactive'}}>Say hi!</a>
<a href="/hello/user" use:link use:active={'/hello/*'}>Say hi with a default className!</a>
<a href="/hello/user" use:link use:active>Say hi with all default options!</a>
The active
action accepts a dictionary options
as argument:
options.path
: the path that, when matched, makes the link active. In the first example above, we want the link to be active when the route is/hello/*
(the asterisk matches anything after that). As you can see, this doesn't have to be the same as the path the link points to. Whenoptions.path
is omitted or false-y, it defaults to the path specified in the link'shref
attribute. This parameter can also be a regular expression that will mark the link as active when it matches: for example, setting to the regular expression/^\/*\/hi$/
will make the link active when it starts with/
and ends with/hi
, regardless of what's in between.options.className
: the name of the CSS class to add. This is optional, and it defaults toactive
if not present.options.inactiveClassName
: the name of the CSS class to add when the link is not active. This is optional, and it defaults to nothing if not present.
As a shorthand, instead of passing a dictionary as options
, you can pass a single string or regular expression that
will be interpreted as options.path
.
Define routes with custom regular expressions
Since version 1.2 of svelte-spa-router, it's possible to define routes using custom regular expressions too, allowing for greater flexibility. However, this requires defining routes using a JavaScript Map rather than an object:
import Home from './routes/Home.svelte'
import Name from './routes/Name.svelte'
import NotFound from './routes/NotFound.svelte'
const routes = new Map()
// You can still use strings to define routes
routes.set('/', Home)
routes.set('/hello/:first/:last?', Name)
// The keys for the next routes are regular expressions
// You will very likely always want to start the regular expression with ^
routes.set(/^\/hola\/(.*)/i, Name)
routes.set(/^\/buongiorno(\/([a-z]+))/i, Name)
// Catch-all, must be last
routes.set('*', NotFound)
When you define routes as regular expressions, the params
prop is populated with an array with the result of the
matches from the regular expression.
For example, with this Name.svelte
route:
<p>Params is: <code>{JSON.stringify(params)}</code></p>
<script>
// You need to define the component prop "params"
export let params = {}
</script>
When visiting #/hola/amigos
, the params prop will be ["/hola/amigos","amigos"]
.
This is consistent with the results of
RegExp.prototype.exec()
.
When defining a route using a regular expression, you can optionally use named capturing groups. When using those, in addition to finding your matches in the
params
prop, you can find the matches for named capturing groups inparams.group
.
For example, consider the route:routes.set(/^\/book\/(?<title>[a-z]+)$/, Book)
When visiting
/#/book/mytitle
, theparams
prop will be an array with["/book/mytitle", "mytitle"]
, andparams.groups
will be a dictionary with{"title": "mytitle"}
.
Advanced usage
Check out the Advanced Usage documentation for using: