Start building a Preact Progressive Web App in seconds ๐ฅ
- Features
- Installation
- Usage
- Official Templates
- CLI Options
- Deploying
- Pre-rendering
- Custom Configuration
- Using CSS preprocessors
- 100/100 Lighthouse score, right out of the box (proof)
- Fully automatic code splitting for routes
- Transparently code-split any component with an
async!
prefix - Auto-generated Service Workers for offline caching powered by Workbox
- PRPL pattern support for efficient loading
- Zero-configuration pre-rendering / server-side rendering hydration
- Support for CSS Modules, LESS, Sass, Stylus; with Autoprefixer
- Monitor your bundle/chunk sizes with built-in tracking
- Automatic app mounting, debug helpers & Hot Module Replacement
- In just 4.5kb you get a productive environment:
- preact
- preact-router
- 1.5kb of conditionally-loaded polyfills for fetch & Promise
Important: Node.js > V6.x is a minimum requirement.
$ npm install -g preact-cli
$ preact create <template-name> <project-name>
Example:
$ preact create default my-project
The above command pulls the template from preactjs-templates/default, prompts for some information, and generates the project at ./my-project/
.
The purpose of official preact project templates are to provide opinionated development tooling setups so that users can get started with actual app code as fast as possible. However, these templates are un-opinionated in terms of how you structure your app code and what libraries you use in addition to preact.js.
All official project templates are repos in the preactjs-templates organization. When a new template is added to the organization, you will be able to run preact create <template-name> <project-name>
to use that template.
Current available templates include:
-
default - Default template with all features.
-
material - material template using preact-material-components
-
simple - The simplest possible preact setup in a single file
-
netlify - Netlify CMS template using preact.
-
typescript - Default template implemented in TypeScript
-
widget - Template for a widget to be embedded in another website.
๐ Tip: Any Github repo with a
'template'
folder can be used as a custom template:
preact create <username>/<repository> <project-name>
Create a project to quick start development.
$ preact create <template-name> <project-name>
--name The application name.
--cwd A directory to use instead of $PWD.
--force Force option to create the directory for the new app [boolean] [default: false]
--yarn Installs dependencies with yarn. [boolean] [default: false]
--git Initialize version control using git. [boolean] [default: false]
--install Installs dependencies. [boolean] [default: true]
Note: If you don't specify enough data to the preact create
command, it will prompt the required questions.
Create a production build
You can disable default: true
flags by prefixing them with --no-<option>
; for example, --no-sw
, --no-esm
, and --no-inline-css
.
$ preact build
--src Specify source directory (default src)
--dest Specify output directory (default build)
--cwd A directory to use instead of $PWD (default .)
--sw Generate and attach a Service Worker (default true)
--json Generate build stats for bundle analysis
--template Path to custom HTML template
--preload Adds preload tags to the document its assets (default false)
--analyze Launch interactive Analyzer to inspect production bundle(s)
--prerenderUrls Path to pre-rendered routes config (default prerender-urls.json)
-c, --config Path to custom CLI config (default preact.config.js)
--esm Builds ES-2015 bundles for your code. (default true)
--brotli Adds brotli redirects to the service worker. (default false)
--inline-css Adds critical css to the prerendered markup. (default true)
-v, --verbose Verbose output
-h, --help Displays this message
Spin up a development server with multiple features like hot-module-replacement
, module-watcher
$ preact watch
--src Specify source directory (default src)
--cwd A directory to use instead of $PWD (default .)
--esm Builds ES-2015 bundles for your code. (default true)
--sw Generate and attach a Service Worker (default false)
--json Generate build stats for bundle analysis
--https Run server with HTTPS protocol
--key Path to PEM key for custom SSL certificate
--cert Path to custom SSL certificate
--cacert Path to optional CA certificate override
--prerender Pre-render static content on first run
--template Path to custom HTML template
--refresh Will use [`Preact-refresh`](https://github.com/JoviDeCroock/preact-refresh) to do hot-reloading
-c, --config Path to custom CLI config (default preact.config.js)
-H, --host Set server hostname (default 0.0.0.0)
-p, --port Set server port (default 8080)
-h, --help Displays this message
Note:
- You can run dev server using
HTTPS
then you can use the followingHTTPS=true preact watch
- You can run the dev server on a different port using
PORT=8091 preact watch
Lists all the official preactjs-cli repositories
$ preact list
Prints debugging information concerning the local environment.
# create a production build:
npm run build
# generate configuration in Firebase Hosting format:
npm run serve -- --server config
# Copy your static files to a server!
Preact CLI in order to follow PRPL pattern renders initial route (/
) into generated static index.html
- this ensures that users get to see your page before any JavaScript is run, and thus providing users with slow devices or poor connection your website's content much faster.
Preact CLI does this by rendering your app inside node - this means that we don't have access to DOM or other global variables available in browsers, similar how it would be in server-side rendering scenarios. In case you need to rely on browser APIs you could:
- drop out of prerendering by passing
--no-prerender
flag topreact build
, - write your code in a way that supports server-side rendering by wrapping code that requires browser's APIs in conditional statements
if (typeof window !== "undefined") { ... }
ensuring that on server those lines of code are never reached. Alternatively you could use a helper library like window-or-global.
To make customizing your configuration easier, preact-cli supports plugins. Visit the Plugins wiki for a tutorial on how to use them.
You may customize your list of supported browser versions by declaring a "browserslist"
key within your package.json
. Changing these values will modify your JavaScript (via babel-preset-env
) and your CSS (via autoprefixer
) output.
By default, preact-cli
emulates the following config:
package.json
{
"browserslist": ["> 1%", "IE >= 9", "last 2 versions"]
}
To customize Babel, you have two options:
-
You may create a
.babelrc
file in your project's root directory. Any settings you define here will overwrite matching config-keys within Preact CLI preset. For example, if you pass a"plugins"
object, it will replace & reset all Babel plugins that Preact CLI defaults to. -
If you'd like to modify or add to the existing Babel config, you must use a
preact.config.js
file. Visit the Webpack section for more info, or check out the Customize Babel example!
To customize preact-cli create a preact.config.js
or a preact.config.json
file.
preact.config.js
// ... imports or other code up here ...
// these props are both optional
export default {
// you can add preact-cli plugins here
plugins: [
// either a function
// (you'd probably import this because you can use the `webpack` function instead of an inline plugin)
function () {},
// strings also work (they get imported by preact-cli), useful for the json config
'plugin-name',
// with options
[
'plugin-name',
{
option: true,
},
],
],
/**
* Function that mutates the original webpack config.
* Supports asynchronous changes when a promise is returned (or it's an async function).
*
* @param {object} config - original webpack config.
* @param {object} env - options passed to the CLI.
* @param {WebpackConfigHelpers} helpers - object with useful helpers for working with the webpack config.
* @param {object} options - this is mainly relevant for plugins (will always be empty in the config), default to an empty object
**/
webpack(config, env, helpers, options) {
/** you can change the config here **/
},
};
See WebpackConfigHelpers docs for more info on helpers
argument which contains methods to find various parts of configuration. Additionally see our recipes wiki containing examples on how to change webpack configuration.
The --prerender
flag will prerender by default only the root of your application.
If you want to prerender other routes you can create a prerender-urls.json
file, which contains the set of routes you want to render.
The format required for defining your routes is an array of objects with a url
key and an optional title
key.
prerender-urls.json
[
{
"url": "/",
"title": "Homepage"
},
{
"url": "/route/random"
}
]
You can customise the path and/or name of prerender-urls.json
by using the flag --prerenderUrls
.
preact build --prerenderUrls src/prerender-urls.json
If a static JSON file is too restrictive, you may want to provide a javascript file that exports your routes instead. Routes can be exported as a JSON string or an object and can optionally be returned from a function.
// prerender-urls.js
module.exports = [
{
url: '/',
title: 'Homepage',
},
{
url: '/route/random',
},
];
A template is used to render your page by EJS.
You can uses the data of prerenderUrls
which does not have title
, using htmlWebpackPlugin.options.CLI_DATA.preRenderData
in EJS.
The default one is visible here and it's going to be enough for the majority of cases.
If you want to customise your template you can pass a custom template with the --template
flag.
The --template
flag is available on the build
and watch
commands.
preact build --template src/template.html
preact watch --template src/template.html
The default templates comes with a .css
file for each component. You can start using CSS preprocessors at any given time during your project lifecycle by installing additional packages and then simply replacing those .css
files.
npm install --save-dev node-sass sass-loader
(inside your preact application folder)- start replacing
.css
files with.scss
files
npm install --save-dev less less-loader
(inside your preact application folder)- start replacing
.css
files with.less
files