Introduction
Use ESM with importmap to manage modern JavaScript in Laravel without transpiling or bundling.
Inspiration
This package was inspired by the Importmap Rails gem. Some pieces of this README were copied straight from there and adapted to the Laravel version.
How does it work?
Import maps let you import JavaScript modules using logical names that map to versioned/digested files – directly from the browser. So you can build modern JavaScript applications using JavaScript libraries made for ES modules (ESM) without the need for transpiling or bundling. This frees you from needing Webpack, Yarn, npm, or any other part of the JavaScript toolchain.
With this approach you'll ship many small JavaScript files instead of one big JavaScript file. Thanks to HTTP/2 that no longer carries a material performance penalty during the initial transport, and in fact offers substantial benefits over the long run due to better caching dynamics. Whereas before any change to any JavaScript file included in your big bundle would invalidate the cache for the the whole bundle, now only the cache for that single file is invalidated.
There's native support for import maps in Chrome/Edge 89+, and a shim available for any browser with basic ESM support. So your app will be able to work with all the evergreen browsers.
Installation
You can install the package via composer:
composer require tonysm/importmap-laravel
The package has an install command that you may run to replace the default Laravel scaffold with one to use importmap:
php artisan importmap:install
Next, we need to add the following component to our view or layout file:
"><x-importmap-tags entrypoint="app" />
Add that between your tags. The entrypoint should be the "main" file, commonly the resources/js/app.js file, which will be mapped to the app module (use the module name, not the file).
We also need to symlink the resources/js folder to public/js to make our JavaScript files publicly available. It's recommended to do that only for local development. This can be achieved by adding the link rule to your config/filesystems.php:
return [
// ...
'links' => array_filter([
public_path('storage') => storage_path('app/public'),
public_path('js') => env('APP_ENV') === 'local' ? resource_path('js') : null,
]),
];
Now, whenever you run php artisan storage:link in the local env, your resources/js folder will be linked to the public/js folder, which will make your imports work while you're developing your app.
For production, it's recommended to run the importmap:optimize command instead:
php artisan importmap:optimize
This should scan all your pinned files/folders (no URLs) and publish them to public/dist/js, adding a digest based on the file's content to the file name - so something like public/dist/js/app-123123.js, and then generate an importmap-manifest.json file in the public/ folder. This file will get precence over your pins. If you run that by accident in development, make sure you delete that file or simply run php artisan importmap:clear, which should get rid of it. You may also want to add /public/dist to your .gitignore file.
Usage
In a nutshell, importmaps works by giving the browser map of where to look for your JavaScript import statements. For instance, you could pin a dependency in the routes/importmap.php file for Alpinejs like so:
use Tonysm\ImportmapLaravel\Facades\Importmap;
// Other pins...
Importmap::pin("alpinejs", to: "https://ga.jspm.io/npm:[email protected]/dist/module.esm.js");
Then, in your JavaScript files you can safely do:
import Alpine from 'alpinejs';
Alpine.start();
window.Alpine = Alpine;
Pinning Local Files
Local pins should be added to the routes/importmap.php file manually, like so:
Importmap::pin("app", to: "/js/app.js");
This means that the app module will point to /js/app.js in the browser. This is a URL or a URI, not the path to file itself. Pins to local file assume a relative path of resources/js/ to find them.
Pinning Local Directories
Declaring all your local files can be tedious, so you may want to map an entire folder like so:
Importmap::pinAllFrom("resources/js/", to: "js/");
When we're generating the importmap JSON, we'll scan that directory looking for any .js or .jsm files inside of it and generating the correct importmap for them based on their relative location. There are a couple interesting rules, though, something like:
| Path | Module | URI |
|---|---|---|
resources/js/app.js |
app |
/js/app.js |
resources/js/controllers/hello_controller.js |
controllers/hello_controller |
/js/controllers/hello_controller.js |
resources/js/libs/index.js |
libs |
/js/libs/index.js |
If there's an index.js file in a folder, we won't get index in the module name, so we can import it like
import libs from 'libs';
Instead of
import libs from 'libs/index';
Pinning External Dependencies
If you depend on any external library you can use the importmap:pin command to pin it, like so:
php artisan importmap:pin alpinejs
That will add the following line to your routes/importmap.php file:
Importmap::pin("alpinejs", to: "https://ga.jspm.io/npm:[email protected]/dist/module.esm.js");
The pin command makes use of the jspm.io API to resolve the dependencies (and the dependencies of our dependencies), looking for ESM modules that we can pin, and resolving it to a CDN URL. We can control the CDN we want to use by specifying the --from flag like so:
php artisan importmap:pin alpinejs --from=unpkg
Which should generate a pin like so:
Importmap::pin("alpinejs", to: "https://unpkg.com/[email protected]/dist/module.esm.js");
It's preferred that you always pin from the same CDN, because then your browser will reuse the same SSL handshake when downloading the files (which means they will be downloaded faster).
Alternatively to using CDNs, you may prefer to vendor the libraries yourself, which you can do by using the --download flag, like so:
php artisan importmap:pin alpinejs --download
This will resolve the dependencies (and the dependencies of our dependencies) and download all the files to your resources/js/vendor folder, which you should add to your version control and maintain yourself. The pin will look like this:
Importmap::pin("alpinejs", to: "/js/vendor/alpinejs.js"); // @3.8.1
The version is added as a comment to your pin so you know which version was imported. Don't remove that as it's gonna be useful later on when you need to upgrade your dependencies.
Preloading Modules
To avoid the waterfall effect where the browser has to load one file after another before it can get to the deepest nested import, we support modulepreload links. Pinned modules can be preloaded by appending preload: true to the pin, like so:
Importmap::pinAllFrom("resources/js/", to: "js/", preload: true);
Importmap::pin("alpinejs", to: "https://unpkg.com/[email protected]/dist/module.esm.js", preload: true); // @3.8.1
Which will add the correct links tags to your head tag in the HTML document, like so:
<link rel="modulepreload" href="https://unpkg.com/[email protected]/dist/module.esm.js">
Known Problems
Browser Console Errors
While import maps are native in Chrome and Edge, they need a shim in other browsers that'll produce a JavaScript console error like TypeError: Module specifier, 'app' does not start with "/", "./", or "../".. This error is normal and does not have any user-facing consequences.
In Firefox, when opening the browser console, the asm.js module lexer build will run in unoptimized mode due to the debugger attaching. This gives a warning message "asm.js type error: Disabled because no suitable wasm compiler is available" which is as expected. When the console is closed again, the asm.js optimizations are fully applied, and this can even be verified with the console open by disabling the debugger in about:config and reloading the page.
On React's JSX and Vue's SFC
It's possible to use both React and Vue with importmaps, but unfortunatelly you would have to use those without the power of JSX or SFC. That's because those file types need a compilation/transpilation step where they are converted to something the browser can understand. There are alternative ways to use both these libraries, but I should say that these are not "common" ways on their communities. You may use React with HTM. And you can use Vue just fine without SFC, the only difference is that your templates would be in Blade files, not a SFC file.
Process ENV Configs
You may be used to having a couple process.env.MIX_* lines in your JS files here and there. The way this works is Webpack would replace at build time your calls to process.env with the values it had during the build. Since we don't have a "build time" anymore, this won't work. Instead, you should add
tags to your layout file with anything that you want to make available to your JavaScript files and use document.head.querySelector('meta[name=my-config]').content instead of relying in the process.env.
Testing
composer test
Changelog
Please see CHANGELOG for more information on what has changed recently.
Contributing
Please see CONTRIBUTING for details.
Security Vulnerabilities
Please review our security policy on how to report security vulnerabilities.
Credits
License
The MIT License (MIT). Please see License File for more information.
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