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Snowpack

什么是 Snowpack ?​

Snowpack 是一种现代，轻量级的工具链，可加快 Web 开发速度。每次保存单个文件时，传统的 JavaScript 构建工具（例如 webpack 和 Parcel）都需要重新构建和重新打包应用程序的分片。 这个重新打包的步骤，在保存更改和在浏览器里看到更改的反映之间引入了一个时间延迟。

Snowpack 在开发的时候不用打包应用。  每个文件只需要构建一次，然后就可以永久缓存。  文件更改时，Snowpack 会重建该单个文件。 没有任何时间浪费在重新打包每个更改上，就是在浏览器中进行即时更新（通过热模块替换（HMR）更快地进行了更新）。 您可以在我们的 Snowpack 2.0 发布帖子中阅读有关此方法的更多信息。

Snowpack 提供不用打包的开发环境，同时也支持你原来生产环境使用的打包方式。当您构建用于生产的应用程序时，可以通过 Snowpack 官方的 Webpack 或 Rollup（即将推出）插件插入您最喜欢的打包器。 Snowpack 已经可以处理您的构建，因此不需要复杂的打包器配置。

Snowpack 为您提供两全其美的优势：在线上打包的时候提供快速，性能优化过的无打包的开发体验。

关键特性​

支持的库​

  • React
  • Preact
  • Svelte
  • Vue
  • lit-html
  • lit-element
  • Styled Components
  • Tailwind CSS
  • 更多

支持的工具​

  • Babel
  • TypeScript
  • PostCSS
  • Sass
  • esbuild
  • 11ty
  • 更多

浏览器支持​

Snowpack 为现代和旧版浏览器构建您的网站。甚至支持 IE 11。您可以使用“ browserlist” package.json 属性控制和自定义此行为。

唯一的要求是，在开发期间必须使用现代的浏览器。 Firefox，Chrome 或 Edge 的任何最新版本都可以。 这是支持现代无打包 ESM 导入所必需的，该导入将您的应用程序加载到浏览器中。

开始

安装 Snowpack​

# 使用 npm
npm install --save-dev snowpack

# 使用 yarn
yarn add --dev snowpack

Snowpack 可以通过 npm install -g Snowpack 全局安装。但是，我们建议在每个项目中通过 --save-dev/--dev 将它安装到本地。你可以通过 package.json 中 scripts npm 的 npx snowpack，或者通过 yarn snowpack 运行 Snowpack 命令。

创建 Snowpack 应用 (CSA)#​

最简单的开始使用 Snowpack 的方法是通过 Create Snowpack App (CSA). CSA 自动初始化一个配置好 Snowpack 开发环境的开始应用。

如果你曾经用过 Create React App，这个和它有些像。

npx create-snowpack-app new-dir --template [SELECT FROM BELOW] [--use-yarn]

官方应用模板#​

迁移一个现有的应用​

将现有的应用程序迁移到 Snowpack 意味着很轻松，因为 Snowpack 支持大多数功能和构建工具，这些功能和构建工具已经在您今天使用（Babel，PostCSS 等）。 如果这是您第一次使用 Snowpack，则应从创建 Snowpack 应用程序（CSA）模板开始，从旧应用程序复制“ src”和“公共”文件，然后运行 snowpack 开发人员，对所有剩余问题进行故障排除。

CSA 是现有应用程序的一个很好的起点，因为它默认情况下内置了一些常用工具（例如 Babel）来复制传统捆绑应用程序的全部功能集。 CSA 还可以替代 Create React App，因此任何现有的 Create React App 项目都应通过 CSA 运行且零更改。 如果您遇到问题，请在我们的文档站点的其余部分中搜索有关从 JS 和 CSS 导入 CSS 的信息，资产引用等。

主要概念​

Unbundled Development#​

Unbundled development is the idea of shipping individual files to the browser during development. Files can still be built with your favorite tools (like Babel, TypeScript, Sass) and then loaded individually in the browser with dependencies thanks to ESM import and export syntax. Any time you change a file, Snowpack only ever needs to rebuild that single file. The alternative is bundled development. Almost every popular JavaScript build tool today focuses on bundled development. Running your entire application through a bundler introduces additional work and complexity to your dev workflow that is unnecessary now that ESM is widely supported. Every change – on every save – must be rebundled with the rest of your application before your changes can be reflected in your browser. Unbundled development has several advantages over the traditional bundled development approach:

  • Single-file builds are fast.
  • Single-file builds are deterministic.
  • Single-file builds are easier to debug.
  • Project size doesn’t affect dev speed.
  • Individual files cache better.

That last point is key: Every file is built individually and cached indefinitely. Your dev environment will never build a file more than once and your browser will never download a file twice (until it changes). This is the real power of unbundled development.

Using NPM Dependencies#​

NPM packages are mainly published using a module syntax (Common.js, or CJS) that can’t run on the web without some build processing. Even if you write your application using browser-native ESM import and export statements that would all run directly in the browser, trying to import any one npm package will force you back into bundled development. Snowpack takes a different approach: Instead of bundling your entire application for this one requirement, Snowpack processes your dependencies separately. Here’s how it works:

node_modules/react/**/*     -> http://localhost:3000/web_modules/react.js
node_modules/react-dom/**/* -> http://localhost:3000/web_modules/react-dom.js
  1. Snowpack scans your website/application for all used npm packages.
  2. Snowpack reads these installed dependencies from your node_modules directory.
  3. Snowpack bundles all of your dependencies separately into single JavaScript files. For example: react and react-dom are converted to react.js and react-dom.js, respectively.
  4. Each resulting file can be run directly in the browser, and imported via ESM import statements.
  5. Because your dependencies rarely change, Snowpack rarely needs to rebuild them.

After Snowpack builds your dependencies, any package can be imported and run directly in the browser with zero additional bundling or tooling required. This ability to import npm packages natively in the browser (without a bundler) is the foundation that all unbundled development and the rest of Snowpack is built on top of.

<!-- This runs directly in the browser with `snowpack dev` -->
<body>
  <script type='module'>    import React from 'react';
    console.log(React);
  </script>
</body>

Snowpack’s Dev Server#​

snowpack dev - Snowpack’s dev server is an instant dev environment for unbundled development. The dev server will only build a file when it’s requested by the browser. That means that Snowpack can start up instantly (usually in <50ms) and scale to infinitely large projects without slowing down. In contrast, it’s common to see 30+ second dev startup times when building large apps with a traditional bundler. Snowpack supports JSX & TypeScript source code by default. You can extend your build even further with custom plugins that connect Snowpack with your favorite build tools: TypeScript, Babel, Vue, Svelte, PostCSS, Sass… go wild!

Snowpack’s Build Pipeline#​

snowpack build - When you’re ready to deploy your application, run the build command to generate a static production build of your site. Building is tightly integrated with your dev setup so that you are guaranteed to get a near-exact copy of the same code that you saw during development.

Bundle for Production#​

You should be able to use a bundler because you want to, and not because you need to. That was the original concept that Snowpack was designed to address. Snowpack treats bundling as an optional production optimization, which means you’re free to skip over the extra complexity of bunling until you need it. By default, snowpack build will build your site using the same unbundled approach as the dev command. This is fine for most projects, but you also may still want to bundle for production. Legacy browser support, code minification, code-splitting, tree-shaking, dead code elimination, and other performance optimizations are all handled in Snowpack via bundling. Connect your favorite bundler to Snowpack via a one-line plugin . Bundlers normally require dozens or even hundreds of lines of configuration, but with Snowpack it’s just a one-line change to your project config file. Snowpack builds your application before sending it to the bundler, so that all the bundler needs to do is worry about bundling the final JavaScript & CSS. No custom configuration required. Snowpack ships with official support for webpack. Connect the "@snowpack/plugin-webpack" plugin in your Snowpack configuration file and then run snowpack build to see your optimized, bundled build.

// snowpack.config.json
// [npm install @snowpack/plugin-webpack]
{
  // Optimize your production builds with Webpack
  "plugins": [["@snowpack/plugin-webpack", {/* ... */}]]
}

JavaScript​

ES Modules (ESM)#​

Snowpack was designed to support JavaScript’s native ES Module (ESM) syntax. ESM lets you define explicit imports & exports that browsers and build tools can better understand and optimize for. If you’re familiar with the import and export keywords in JavaScript, then you already know ESM!

// ESM Example - src/user.js
export function getUser() { /* ... */
// src/index.js
import {getUser} from './user.js';

All modern browsers support ESM, so Snowpack is able to ship this code directly to the browser during development. This is what makes Snowpack’s unbundled development workflow possible. Snowpack also lets you import non-JavaScript files directly in your application. Snowpack handles all this for you automatically so there’s nothing to configure, using the following logic:

Import NPM Packages#​

// Returns the React & React-DOM npm packages
import React from 'react';
import ReactDOM from 'react-dom';

Snowpack lets you import npm packages directly in the browser. Even if a package was published using a legacy format, Snowpack will up-convert the package to ESM before serving it to the browser. When you start up your dev server or run a new build, you may see a message that Snowpack is “installing dependencies”. This means that Snowpack is converting your dependencies to run in the browser.

Import JSON#​

// Returns the JSON object via the default import
import json from './data.json';

Snowpack supports importing JSON files, which return the full JSON object in the default import.

Import CSS#​

// Loads './style.css' onto the page
import './style.css';

Snowpack supports basic CSS imports inside of your JavaScript files. When you import a CSS file via the import keyword, Snowpack will automatically apply those styles to the page. This works for CSS and compile-to-CSS languages like Sass & Less. If you prefer, Snowpack also supports any popular CSS-in-JS library for styling.

Import CSS Modules#​

/* src/style.module.css */
.error {
  background-color: red;
}
// 1. Converts './style.module.css' classnames to unique, scoped values.
// 2. Returns an object mapping the original classnames to their final, scoped value.
import styles from './style.module.css';
// This example uses JSX, but you can use CSS Modules with any framework.
return <div className={styles.error}>Your Error Message</div>;

Snowpack supports CSS Modules using the [name].module.css naming convention. CSS Modules work just like normal CSS imports, but with a special default styles export that maps your original classnames to unique identifiers.

Import Images & Other Assets#​

import img from './image.png'; // img === '/src/image.png'
import svg from './image.svg'; // svg === '/src/image.svg'
// This example uses JSX, but you can use these references with any framework.
<img src={img} />;

All other assets not explicitly mentioned above can be imported and will return a URL reference to the final built asset. This can be useful for referencing non-JS assets by URL, like creating an image element with a src attribute pointing to that image.

Features​

Snowpack ships with built-in support for the following file types, no configuration required:

  • JavaScript (.js, .mjs)
  • TypeScript (.ts, .tsx)
  • JSX (.jsx, .tsx)
  • CSS (.css)
  • CSS Modules (.module.css)
  • Images (.svg, .jpg, .png, etc.)

To customize build behavior and support new languages (.scss, .svelte, .vue), keep reading.

Import Aliases#​

// Instead of this:
import Button from `../../../../components/Button`;
// You can do this:
import Button from `@app/components/Button`;

Snowpack supports setting custom import aliases for your project via the top-level alias property. This can be used to define an alias for either a local source directory (like aliasing @app to ./src) or a package (like aliasing react to preact/compat). See the full documentation for alias below. TypeScript Users: You’ll need to configure your tsconfig.json paths to get proper types from top-level imports. Learn more about “path mappings”.

// tsconfig.json
{
  "compilerOptions": {
    "baseUrl": ".",
    "paths": {
      // Define either ONE of these...
      // 1. General support: matches everything relative to the project directory
      "*": ["*"],
      // 2. Explicit support: match only your mounted directories (Recommended!)
      "src/*": ["src/*"],
      "public/*": ["public/*"],
    }
  }
}

Environment Variables#​

// `import.meta.env` - Read process.env variables in your web app
fetch(`${import.meta.env.SNOWPACK_PUBLIC_API_URL}/users`).then(...)
// Supports destructuring as well:
const {SNOWPACK_PUBLIC_API_URL} = import.meta.env;
fetch(`${SNOWPACK_PUBLIC_API_URL}/users`).then(...)
// Instead of `import.meta.env.NODE_ENV` use `import.meta.env.MODE`
if (import.meta.env.MODE === 'development') {
  // ...

You can read environment variables directly in your web application via import.meta.env. If you’ve ever used process.env in Create React App or any Webpack application, this behaves exactly the same. For your safety, Snowpack only supports environment variables that begin with SNOWPACK_PUBLIC_*. We do this because everything in your web application is sent to the browser, and we don’t want you to accidentally share sensitive keys/env variables with your public web application. Prefixing your frontend web env variables with SNOWPACK_PUBLIC_ is a good reminder that they will be shared with the world. import.meta.env.MODE and import.meta.env.NODE_ENV are also both set to the current process.env.NODE_ENV value, so that you can change app behavior based on dev vs. build. The env value is set to development during snowpack dev and production during snowpack build. Use this in your application instead of process.env.NODE_ENV. Remember: that these env variables are statically injected into your application for everyone at build time, and not runtime.

.ENV FILE SUPPORT​

// snowpack.config.json
{
  "plugins": ["@snowpack/plugin-dotenv"]
}

Add the @snowpack/plugin-dotenv plugin to your dev environment to automatically load environment variables from your project .env files. Visit the plugin README to learn more.

Hot Module Replacement#​

Hot Module Replacement (HMR) is the ability to update your web app during development without refreshing the page. Imagine changing some CSS, hitting save, and then instantly seeing your change reflected on the page without a refresh. That’s HMR. Snowpack supports full HMR out-of-the-box for the following served files:

  • CSS
  • CSS Modules
  • JSON

Popular frameworks can also be set up for HMR. Create Snowpack App (CSA) ships with HMR enabled by default for all of the following frameworks. If you’re not using CSA, you can setup HMR in your application with a simple plugin or a few lines of code:

For more advanced, bare-metal HMR integrations, Snowpack created ESM-HMR, a standard HMR API for any ESM-based dev environment. Any HMR integration built for ESM-HMR will run on Snowpack and any other ESM-HMR-enabled dev server. To use the HMR API directly (via import.meta.hot) check out the ESM-HMR spec to learn more.

if (import.meta.hot) {
  import.meta.hot.accept(({module}) => {
    // Accept the module, apply it to your application.
  });
  import.meta.hot.dispose(() => {
    // Cleanup any side-effects. Optional.
  });
}

Dev Request Proxy#​

// snowpack.config.json
// Example: Proxy "/api/pokemon/ditto" -> "https://pokeapi.co/api/v2/pokemon/ditto"
{
  "proxy": {
    "/api": "https://pokeapi.co/api/v2",
  }
}

Snowpack can proxy requests from the dev server to external URLs and APIs. Making API requests directly the dev server can help you mimic your production environment during development. See the Proxy Options section for more information and full set of configuration options.

HTTPS/HTTP2#​

npm start -- --secure

Snowpack provides an easy way to use a local HTTPS server during development through the use of the --secure flag. When enabled, Snowpack will look for a snowpack.key and snowpack.crt file in the root directory and use that to create an HTTPS server with HTTP2 support enabled.

GENERATING SSL CERTIFICATES​

You can automatically generate credentials for your project via either:

Legacy Browser Support#​

You can customize the set of browsers you’d like to support via the package.json “browserslist” property, going all the way back to IE11. This will be picked up when you run snowpack build to build for production.

/* package.json */
"browserslist": ">0.75%, not ie 11, not UCAndroid >0, not OperaMini all",

If you’re worried about legacy browsers, you should also add a bundler to your production build. Check out our section on bundling for production for more info. Note: During development (snowpack dev) we perform no transpilation for older browsers. Make sure that you’re using a modern browser during development.

Configuration​

Snowpack’s behavior can be configured by CLI flags, a custom Snowpack config file, or both. See the table below for the full list of supported options.

Config Files#​

Snowpack supports configuration files in multiple formats, sorted by priority order:

  1. --config [path]: If provided.
  2. package.json: A namespaced config object ("snowpack": {...}).
  3. snowpack.config.js: (module.exports = {...}).
  4. snowpack.config.json: ({...}).

CLI Flags#​

# Show helpful info
$ snowpack --help
# Show additional debugging logs
$ snowpack --log-level=debug
# {installOptions: {dest: 'CUSTOM_DIR/'}}
$ snowpack install --dest CUSTOM_DIR/
# {devOptions: {bundle: true}}
$ snowpack dev --bundle
# {devOptions: {bundle: false}}
$ snowpack dev --no-bundle
# {buildOptions: {minify: false}}
$ snowpack build --no-minify

CLI flags will be merged with (and take priority over) your config file values. Every config value outlined below can also be passed as a CLI flag. Additionally, Snowpack also supports the following flags:

  • --config [path] Set the path to your project config file.
  • --help Show this help.
  • --version Show the current version.
  • --reload Clear the local cache. Useful for troubleshooting installer issues.

All Config Options#​

{
  "install": [
    "htm",
    "preact",
    "preact/hooks", // A package within a package
    "unistore/full/preact.es.js", // An ESM file within a package (supports globs)
    "bulma/css/bulma.css" // A non-JS static asset (supports globs)
  ],
  "mount": { /* ... */ },
  "proxy": { /* ... */ },
  "plugins": [ /* ... */ ],
  "installOptions": { /* ... */ },
  "devOptions": { /* ... */ },
  "buildOptions": { /* ... */ },
}

TOP-LEVEL OPTIONS​

  • extends|string
    • Inherit from a separate “base” config. Can be a relative file path, an npm package, or a file within an npm package. Your configuration will be merged on top of the extended base config.
  • exclude|string[]
    • Exclude any files from scanning, building, etc. Defaults to exclude common test file locations: ['**/node_modules/**/*', '**/__tests__/*', '**/*.@(spec|test).@(js|mjs)']
    • Useful for excluding tests and other unnecessary files from the final build. Supports glob pattern matching.
  • install|string[]
    • Known dependencies to install with Snowpack. Useful for installing packages manually and any dependencies that couldn’t be detected by our automatic import scanner (ex: package CSS files).
  • mount.*
    • Mount local directories to custom URLs in your built application.
  • alias.*
    • Configure import aliases for directories and packages. See the section below for all options.
  • proxy.*
    • Configure the dev server to proxy requests. See the section below for all options.
  • plugins
    • Extend Snowpack with third-party tools and plugins. See the section below for more info.
  • installOptions.*
    • Configure how npm packages are installed. See the section below for all options.
  • devOptions.*
    • Configure your dev server. See the section below for all options.
  • buildOptions.*
    • Configure your build. See the section below for all options.

INSTALL OPTIONS​

  • dest|string
    • Default:"web_modules"
    • Configure the install directory.
  • sourceMap|boolean
    • Emit source maps for installed packages.
  • env|{[ENV_NAME: string]: (string | true)}
    • Sets a process.env. environment variable inside the installed dependencies. If set to true (ex: {NODE_ENV: true} or --env NODE_ENV) this will inherit from your current shell environment variable. Otherwise, set to a string (ex: {NODE_ENV: 'production'} or --env NODE_ENV=production) to set the exact value manually.
  • treeshake|boolean
    • Default:false, or true when run with snowpack build
    • Treeshake your dependencies to optimize your installed files. Snowpack will scan your application to detect which exact imports are used from each package, and then will remove any unused imports from the final install via dead-code elimination (aka tree shaking).
  • installTypes|boolean
    • Install TypeScript type declarations with your packages. Requires changes to your tsconfig.json to pick up these types.
  • alias|{[mapFromPackageName: string]: string}
    • Alias an installed package name. This applies to imports within your application and within your installed dependency graph.
    • Example: "alias": {"react": "preact/compat", "react-dom": "preact/compat"}
  • namedExports|string[]
    • Legacy Common.js (CJS) packages should only be imported by the default import (Example: import reactTable from 'react-table')
    • But, some packages use named exports in their documentation, which can cause confusion for users. (Example: import {useTable} from 'react-table')
    • You can enable “fake/synthetic” named exports for Common.js package by adding the package name under this configuration.
    • Example: "namedExports": ["react-table"]
  • rollup
    • Snowpack uses Rollup internally to install your packages. This rollup config option gives you deeper control over the internal rollup configuration that we use.
    • rollup.plugins - Specify Custom Rollup plugins if you are dealing with non-standard files.
    • rollup.dedupe - If needed, deduplicate multiple versions/copies of a packages to a single one. This helps prevent issues with some packages when multiple versions are installed from your node_modules tree. See rollup-plugin-node-resolve for more documentation.

DEV OPTIONS​

  • port|number| Default:8080
    • The port number to run the dev server on.
  • out|string| Default:"build"
    • The local directory that we output your final build to.
  • bundle|boolean
    • Create an optimized, bundled build for production.
    • You must have Parcel as a dev dependency in your project.
    • If undefined, this option will be enabled if the parcel package is found.
  • fallback|string| Default:"index.html"
    • When using the Single-Page Application (SPA) pattern, this is the HTML “shell” file that gets served for every (non-resource) user route. Make sure that you configure your production servers to serve this as well.
  • open|string| Default:"default"
    • Opens the dev server in a new browser tab. If Chrome is available on macOS, an attempt will be made to reuse an existing browser tab. Any installed browser may also be specified. E.g., “chrome”, “firefox”, “brave”. Set “none” to disable.
  • hostname|string| Default:localhost
    • The hostname where the browser tab will be open.
  • hmr|boolean| Default:true
    • Toggles whether or not Snowpack dev server should have HMR enabled.
  • secure|boolean
    • Toggles whether or not Snowpack dev server should use HTTPS with HTTP2 enabled.

BUILD OPTIONS​

  • baseUrl|string| Default:/
    • In your HTML, replace all instances of %PUBLIC_URL% with this (inspired by the same Create React App concept). This is useful if your app will be deployed to a subdirectory. Note: if you have homepage in your package.json, Snowpack will actually pick up on that, too.
  • clean|boolean| Default:false
    • Set to true if Snowpack should erase the build folder before each build.
  • metaDir|string| Default:__snowpack__
    • By default, Snowpack outputs Snowpack-related metadata such as HMR and ENV info to a folder called __snowpack__. You can rename that folder with this option (e.g.: metaDir: 'static/snowpack').
  • minify|boolean| Default:true
    • By default, Snowpack will minify your dependencies on snowpack build. Disable this by setting this config option to minify: false.
  • sourceMaps|boolean| Default:false
    • Experimental: Set to true to enable source maps
  • webModulesUrl|string| Default:web_modules
    • Rename your web modules directory.

PROXY OPTIONS​

// snowpack.config.json
{
  "proxy": {
    // Short form:
    "/api/01": "https://pokeapi.co/api/v2/",
    // Long form:
    "/api/02": {
      on: { proxyReq: (p, req, res) => /* Custom event handlers (JS only) */ },
      /* Custom http-proxy options */
    }
  }
}

If desired, "proxy" is where you configure the proxy behavior of your dev server. Define different paths that should be proxied, and where they should be proxied to. The short form of a full URL string is enough for general use. For advanced configuration, you can use the object format to set all options supported by http-proxy. on is a special property for setting event handler functions on proxy server events. See the section on “Listening for Proxy Events” for a list of all supported events. You must be using a snowpack.config.js JavaScript configuration file to set this. This configuration has no effect on the final build.

MOUNT OPTIONS​

// snowpack.config.json
{
  "mount": {
    // Files in the local "src/" directory are written to `/_dist_/*` in the final build.
    "src": "/_dist_",
    // Files in the local "public/" directory are written to `/*` in the final build.
    "public": "/"
    // … add other folders here
  }
}

The mount configuration lets you map local files to their location in the final build. If no mount configuration is given, then the entire current working directory (minus excluded files) will be built and mounted to the Root URL (Default: /, respects baseUrl).

ALIAS OPTIONS​

Note: In an older version of Snowpack, all mounted directories were also available as aliases by default. As of Snowpack 2.7, this is no longer the case and no aliases are defined by default.

// snowpack.config.json
{
  alias: {
    // Type 1: Package Import Alias
    "lodash": "lodash-es",
    "react": "preact/compat",
    // Type 2: Local Directory Import Alias (relative to cwd)
    "components": "./src/components"
    "@app": "./src"
  }
}

The alias config option lets you define an import alias in your application. When aliasing a package, this allows you to import that package by another name in your application. This applies to imports inside of your dependencies as well, essentially replacing all references to the aliased package. Aliasing a local directory (any path that starts with “./”) creates a shortcut to import that file or directory. While we don’t necessarily recommend this pattern, some projects do enjoy using these instead of relative paths:

-import '../../../../../Button.js';+import '@app/Button.js';

Plugins​

Snowpack isn’t just a build tool for JavaScript, it is a build tool for your entire website. Babel, TypeScript, PostCSS, SVGR and any favorite build tool can be connected directly into Snowpack via 1-line plugins. Snowpack plugins can be added to:

  • Customize your build with new language/framework support (Svelte, Vue)
  • Customize your build with new build tools (Babel, PostCSS)
  • Run CLI commands during build and development (TypeScript, ESLint)
  • Create custom transformations, specific to your exact application.

👉 Check out our advanced guide and learn how to create your own plugin.

Connect a Plugin#​

To make a plugin available, you have to put it in your project devDependencies list (package.json) which will install it locally (in your project) and make it available to snowpack. For the official snowpack plugins, command would look like:

# for npm
npm install --save-dev @snowpack/[plugin-name]
# for yarn
yarn add --dev @snowpack/[plugin-name]

After that, you can connect the plugin to Snowpack via the "plugins" array in your Snowpack config. For example,

// snowpack.config.json
{
  "plugins": ["@snowpack/plugin-babel"]
}

This is all you need to add Babel to your application build pipeline. If the plugin supports it, you can also pass options to the plugin to configure its behavior:

// snowpack.config.json
{
  "plugins": [
    ["@snowpack/plugin-babel", { /* ... */}]
  ],
}

NOTE: The order of plugins is important, for example, if there are multiple plugins that load/build particular type of file, the first matching will take precedence. If it succeeds in the build task for the file, others will not be called for that particular build task.

Connect any Script/CLI#​

If you can’t find a plugin that fits your needs and don’t want to write your own, you can also run CLI commands directly as a part of your build using one of our two utility plugins: @snowpack/plugin-build-script & @snowpack/plugin-run-script.

@SNOWPACK/PLUGIN-BUILD-SCRIPT​

// snowpack.config.json
// [npm install @snowpack/plugin-build-script]
{
  "plugins": [
    ["@snowpack/plugin-build-script", { "cmd": "postcss", "input": [".css"], "output": [".css"]}]
  ],
}

This plugin allows you to connect any CLI into your build process. Just give it a cmd CLI command that can take input from stdin and emit the build result via stdout. Check out the README for more information.

@SNOWPACK/PLUGIN-RUN-SCRIPT​

// snowpack.config.json
// [npm install @snowpack/plugin-run-script]
{
  "plugins": [
    ["@snowpack/plugin-run-script", { "cmd": "tsc --noEmit", "watch": "$1 --watch"}]
  ],
}

This plugin allows you to run any CLI command as a part of your dev and build workflow. This plugin doesn’t affect your build output, but it is useful for connecting developer tooling directly into Snowpack. Use this to add meaningful feedback to your dev console as you type, like TypeScript type-checking and ESLint lint errors.

Official Plugins#​

👉 Check out our full list of official plugins.

Community Plugins#​

Don’t see your plugin in this list? Add yours!

Recipes​

Below are a collection of guides for using different web frameworks and build tools with Snowpack. If you’d like to contribute a new recipe, feel free to edit the docs to add your own.

Supported Libraries#​

All of the following frameworks have been tested and guaranteed to work in Snowpack without issues. If you encounter an issue using any of the following, please file an issue.

  • React
  • Preact
  • JSX
  • HTM
  • lit-html
  • Vue (see below)
  • Svelte (see below)
  • Tailwind CSS (see below)
  • Sass (see below)
  • and many more!
  • Literally… every library should work with Snowpack!

Some libraries use compile-to-JS file formats and do require a special build script or plugin. See the guide below for examples.

JSX#​

Snowpack has built-in support to handle .jsx & .tsx source files in your application. Note: Snowpack’s default build does not support JSX in .js/.ts files. If you can’t use the .jsx/.tsx file extension, you can use Babel to build your application instead.

TypeScript#​

Snowpack has built-in support to handle .ts & .tsx source files in your application. Snowpack supports live TypeScript type checking right in the Snowpack CLI dev console. Connect the TypeScript compiler (tsc) into your workflow using the snippet below.

// snowpack.config.json
// Example: Connect TypeScript CLI (tsc) reporting to Snowpack
{
  "plugins": [
    ["@snowpack/plugin-run-script", {"cmd": "tsc --noEmit", "watch": "$1 --watch"}]
  ]
}

Babel#​

Snowpack already comes with built-in support for building JavaScript, TypeScript, and JSX. However, If you would like to run your build through Babel instead, you can replace our default file builder with the official Snowpack Babel plugin. The plugin will automatically read plugins & presets from your local project babel.config.* config file, if one exists.

// snowpack.config.json
"plugins": ["@snowpack/plugin-babel"],

Preact#​

You can import and use Preact without any custom configuration needed. To use preact/compat: (the Preact+React compatability layer) alias the “compat” package to React in your install options:

// Example: Lets you import "react" in your application, but uses preact internally
// snowpack.config.json
"installOptions": {
  "alias": {
    "react": "preact/compat",
    "react-dom": "preact/compat"
  }
}

Vue#​

// snowpack.config.json
"plugins": ["@snowpack/plugin-vue"]

Svelte#​

// snowpack.config.json
"plugins": ["@snowpack/plugin-svelte"]

PostCSS#​

// snowpack.config.json
"plugins": [
  ["@snowpack/plugin-build-script", {"cmd": "postcss", "input": [".css"], "output": [".css"]}]
]

The postcss-cli package must be installed manually. You can configure PostCSS with a postcss.config.js file in your current working directory.

CSS @import Support#​

The @import statements in CSS files are not yet supported natively, meaning an @import 'foo/bar.css' (with a relative URL) will by default look for foo/bar.css in your app’s public/ directory only. To allow relative @imports from the CSS files in your src/ directory and to import CSS from other node_modules:

// postcss.config.js
module.exports = {
  plugins: [
    // ...
    require('postcss-import')({path: ['resources/css']}),
    // ...
  ]
  • If you’re migrating an existing app to snowpack, note that @import '~package/...' (URL starting with a tilde) is a syntax specific to webpack. With postcss-import you have to remove the ~ from your @imports.

Alternatively use import 'path/to/css'; in your JS files without any configuration.

Tailwind CSS#​

// postcss.config.js
// Taken from: https://tailwindcss.com/docs/installation#using-tailwind-with-postcss
module.exports = {
  plugins: [
    // ...
    require('tailwindcss'),
    require('autoprefixer'),
    // ...
  ]
}

Tailwind ships with first-class support for PostCSS. To use Tailwind in your Snowpack project, connect PostCSS (see above) and add the recommended Tailwind PostCSS plugin to your snowpack configuration. Follow the official Tailwind CSS Docs for more info.

Sass#​

// snowpack.config.json
// Example: Build all src/css/*.scss files to public/css/*
"plugins": [
  ["@snowpack/plugin-run-script", {"cmd": "sass src/css:public/css --no-source-map", "watch": "$1 --watch"}]
]
// You can configure this to match your preferred layout:
//
// import './App.css';
// "run:sass": "sass src:src --no-source-map",
//
// import 'public/css/App.css';
// "run:sass": "sass src/css:public/css --no-source-map",
// (Note: Assumes mounted public/ directory ala Create Snowpack App)

Sass is a stylesheet language that’s compiled to CSS. It allows you to use variables, nested rules, mixins, functions, and more, all with a fully CSS-compatible syntax. Sass helps keep large stylesheets well-organized and makes it easy to share design within and across projects. Check out the official Sass CLI documentation for a list of all available arguments. You can also use the node-sass CLI if you prefer to install Sass from npm. Note: Sass should be run as a “run:” script (see example above) to take advantage of the Sass CLI’s partial handling. A "build:scss" script would build each file individually as its served, but couldn’t handle Sass partials via @use due to the fact that Sass bundles these into the importer file CSS. To use Sass + PostCSS, check out this guide.

ESLint#​

// snowpack.config.json
"plugins": [
  ["@snowpack/plugin-run-script", {
    "cmd": "eslint 'src/**/*.{js,jsx,ts,tsx}'",
    // Optional: Use npm package "watch" to run on every file change
    "watch": "watch \"$1\" src"
  }]
]

Webpack#​

// snowpack.config.json
{
  // Optimize your production builds with Webpack
  "plugins": [["@snowpack/plugin-webpack", {/* ... */}]]
}

Snowpack ships an official webpack plugin for optimizing your build. Connect the "@snowpack/plugin-webpack" plugin into your Snowpack configuration file and then run snowpack build to see your optimized, bundled build.

Workbox#​

The Workbox CLI integrates well with Snowpack. Run the wizard to bootstrap your first configuration file, and then run workbox generateSW to generate your service worker. Remember that Workbox expects to be run every time you deploy, as a part of a production build process. If you don’t have one yet, create package.json "deploy" and/or "build" scripts to automate your production build process.

Server Side Rendering (SSR)#​

To connect your own server to snowpack dev for SSR, there are a few things that you’ll need to set up. Make sure that you include any Snowpack-built resources via script tags in your server’s HTML response:

<!-- Example: Create Snowpack App builds your src/ directory to the /_dist_/* directory -->
<script type="module" src="http://localhost:8080/_dist_/index.js"></script>

And make sure that your HTML response also includes code to configure HMR to talk to Snowpack’s dev server:

<!-- Configure Snowpack's HMR connection yourself, somewhere on your page HTML -->
<script>window.HMR_WEBSOCKET_URL = "ws://localhost:8080"</script>

Leaving Snowpack#​

Snowpack is designed for zero lock-in. If you ever feel the need to add a traditional application bundler to your stack (for whatever reason!) you can do so in seconds. Any application built with Snowpack should Just Work™️ when passed through Webpack/Rollup/Parcel. If you are already importing packages by name in your source code (ex: import React from 'react') then you should be able to migrate to any popular bundler without issue. If you are importing packages by full URL (ex: import React from '/web_modules/react.js'), then a simple Find & Replace should help you re-write them to the plain package name imports that most bundlers expect.

Troubleshooting​

Node built-in could not be resolved#​

✖ /my-application/node_modules/dep/index.js
  "http" (Node.js built-in) could not be resolved.

Some packages are written with dependencies on Node.js built-in modules. This is a problem on the web, since Node.js built-in modules don’t exist in the browser. For example, import 'path' will run just fine in Node.js but would fail in the browser. To solve this issue: you can either replace the offending package (pika.dev is a great resource for web-friendly packages) or add Node.js polyfill support:

// snowpack.config.js
// Plugin: https://github.com/ionic-team/rollup-plugin-node-polyfills
module.exports = {
  installOptions: {
    rollup: {
      plugins: [require('rollup-plugin-node-polyfills')()],
    },
  },
};

No such file or directory#​

ENOENT: no such file or directory, open …/node_modules/csstype/index.js

This error message would sometimes occur in older versions of Snowpack. To solve this issue: Upgrade to Snowpack v2.6.0 or higher. If you continue to see this unexpected error in newer versions of Snowpack, please file an issue.

Package exists but package.json “exports” does not include entry#​

Node.js recently added support for a package.json “exports” entry that defines which files you can and cannot import from within a package. Preact, for example, defines an “exports” map that allows you to to import “preact/hooks” but not “preact/some/custom/file-path.js”. This allows packages to control their “public” interface. If you see this error message, that means that you’ve imported a file path not allowed in the export map. If you believe this to be an error, reach out to the package author to request the file be added to their export map.

Assets​

参考