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Eleventy Dev Server Added in v2.0.0

Contents

Options
- onRequest for request-time processing
Advanced chokidar options
Swap back to Browsersync
- setBrowserSyncConfig

The Eleventy 2.0 release includes a brand new development server. Check out the 11ty/eleventy-dev-server repository on GitHub.

At time of release, this new server has:

🏋🏻‍♀️ Minimal footprint: 1.4 MB node_modules
- Eleventy node_modules dropped from 155 MB to 34.3 MB
- Faster Eleventy npm install times (30.5% faster)
- Reduced Eleventy dependency count from 311 -> 211
📦 Bundler Decoupled
🚄 Fast ~2ms startup times
⚡️ WebSockets-based Live reload
🔬 DOM-diffing HTML updates
⚠️ No unresolved npm audit errors or warnings 👀
🚤 Supports emulated passthrough file copy for faster builds!

Read more detail on the Eleventy Dev Server 1.0 release notes.

Options

You can configure the server with the new setServerOptions Configuration API method.

eleventy.config.js

ESM CommonJS

export default function(eleventyConfig) {
	eleventyConfig.setServerOptions({
		// Default values are shown:

		// Whether the live reload snippet is used
		liveReload: true,

		// Whether DOM diffing updates are applied where possible instead of page reloads
		domDiff: true,

		// The starting port number
		// Will increment up to (configurable) 10 times if a port is already in use.
		port: 8080,

		// Additional files to watch that will trigger server updates
		// Accepts an Array of file paths or globs (passed to `chokidar.watch`).
		// Works great with a separate bundler writing files to your output folder.
		// e.g. `watch: ["_site/**/*.css"]`
		watch: [],

		// Show local network IP addresses for device testing
		showAllHosts: false,

		// Use a local key/certificate to opt-in to local HTTP/2 with https
		https: {
			// key: "./localhost.key",
			// cert: "./localhost.cert",
		},

		// Change the default file encoding for reading/serving files
		encoding: "utf-8",

		// Show the dev server version number on the command line
		showVersion: false,

		// Added in Dev Server 2.0+
		// The default file name to show when a directory is requested.
		indexFileName: "index.html",

		// Added in Dev Server 2.0+
		// An object mapping a URLPattern pathname to a callback function
		// for on-request processing (read more below).
		onRequest: {},
	});
};

module.exports = function(eleventyConfig) {
	eleventyConfig.setServerOptions({
		// Default values are shown:

		// Whether the live reload snippet is used
		liveReload: true,

		// Whether DOM diffing updates are applied where possible instead of page reloads
		domDiff: true,

		// The starting port number
		// Will increment up to (configurable) 10 times if a port is already in use.
		port: 8080,

		// Additional files to watch that will trigger server updates
		// Accepts an Array of file paths or globs (passed to `chokidar.watch`).
		// Works great with a separate bundler writing files to your output folder.
		// e.g. `watch: ["_site/**/*.css"]`
		watch: [],

		// Show local network IP addresses for device testing
		showAllHosts: false,

		// Use a local key/certificate to opt-in to local HTTP/2 with https
		https: {
			// key: "./localhost.key",
			// cert: "./localhost.cert",
		},

		// Change the default file encoding for reading/serving files
		encoding: "utf-8",

		// Show the dev server version number on the command line
		showVersion: false,

		// Added in Dev Server 2.0+
		// The default file name to show when a directory is requested.
		indexFileName: "index.html",

		// Added in Dev Server 2.0+
		// An object mapping a URLPattern pathname to a callback function
		// for on-request processing (read more below).
		onRequest: {},
	});
};

Expand to see the Full options list

eleventy.config.js

ESM CommonJS

export default function(eleventyConfig) {
	eleventyConfig.setServerOptions({
		// Change the name of the folder name used for injected scripts
		injectedScriptsFolder: ".11ty",

		// Number of times to increment a port is already in use
		portReassignmentRetryCount: 10,

		// Alias for backwards compatibility, renamed to `injectedScriptsFolder` in Dev Server 1.0+
		folder: ".11ty",

		// Alias for backwards compatibility, renamed to `liveReload` in Dev Server 1.0+
		enabled: true,

		// Alias for backwards compatibility, renamed to `domDiff` in Dev Server 1.0+
		domdiff: true,
	});
};

module.exports = function(eleventyConfig) {
	eleventyConfig.setServerOptions({
		// Change the name of the folder name used for injected scripts
		injectedScriptsFolder: ".11ty",

		// Number of times to increment a port is already in use
		portReassignmentRetryCount: 10,

		// Alias for backwards compatibility, renamed to `injectedScriptsFolder` in Dev Server 1.0+
		folder: ".11ty",

		// Alias for backwards compatibility, renamed to `liveReload` in Dev Server 1.0+
		enabled: true,

		// Alias for backwards compatibility, renamed to `domDiff` in Dev Server 1.0+
		domdiff: true,
	});
};

Read more about chokidar.watch compatible paths for the watch option. Advanced chokidar configuration is available.
For a full list of encoding values supported by Node (also used in the Content-Type HTTP Header), check out Node’s Buffer documentation.
Using a root 404.html file (a popular convention supported by Netlify, GitHub Pages, Vercel, and others) supported! We use the content from a 404.html in your output folder when serving the error page for missing content.

INFO:

Try out the devcert-cli package to generate a localhost key and certificate for https and HTTP/2.

`onRequest` for request-time processing

Added in v3.0.0Added in Dev Server 2.0.0 Use the new onRequest object to configure some of your project to use on-request-time processing. The keys in this object represent strings from the URL Pattern API.

eleventy.config.js

ESM CommonJS

export default function(eleventyConfig) {
	eleventyConfig.setServerOptions({
		onRequest: {
			"/": function({ url }) {
				// will fallback to serve static files if we return any falsy value other than ""
			},
			"/empty": function({ url }) {
				// render an empty page
				return "";
			},
			"/foo/:name": function({ url, pattern, patternGroups }) {
				// patternGroups will include URLPattern matches e.g. /foo/zach => { name: "zach" }
				return {
					status: 200,
					headers: {
						"Content-Type": "text/html",
					},
					body: "Hello."
				};
			}
		}
	});
};

module.exports = function(eleventyConfig) {
	eleventyConfig.setServerOptions({
		onRequest: {
			"/": function({ url }) {
				// will fallback to serve static files if we return any falsy value other than ""
			},
			"/empty": function({ url }) {
				// render an empty page
				return "";
			},
			"/foo/:name": function({ url, pattern, patternGroups }) {
				// patternGroups will include URLPattern matches e.g. /foo/zach => { name: "zach" }
				return {
					status: 200,
					headers: {
						"Content-Type": "text/html",
					},
					body: "Hello."
				};
			}
		}
	});
};

Works great with the process.env.ELEVENTY_RUN_MODE environment variable to change how your server operates during--serve mode.

eleventy.config.js

ESM CommonJS

export default function(eleventyConfig) {
	// Intercept all requests during --serve mode.
	if(process.env.ELEVENTY_RUN_MODE === "serve") {
		eleventyConfig.setServerOptions({
			onRequest: {
				"/*": function({ url }) {
					// Don’t return any static files, only show a help message
					return "Help I am trapped in the computer.";
				},
			}
		});
	}
};

module.exports = function(eleventyConfig) {
	// Intercept all requests during --serve mode.
	if(process.env.ELEVENTY_RUN_MODE === "serve") {
		eleventyConfig.setServerOptions({
			onRequest: {
				"/*": function({ url }) {
					// Don’t return any static files, only show a help message
					return "Help I am trapped in the computer.";
				},
			}
		});
	}
};

Advanced `chokidar` options

Access to advanced chokidar configuration is available via the eleventyConfig.setChokidarConfig method (on the Watch and Serve documentation).

Swap back to Browsersync Added in v2.0.0

You can swap back to Eleventy Dev Server using the setServerOptions configuration API and the @11ty/eleventy-server-browsersync package.

First, install it:

npm install @11ty/eleventy-server-browsersync

Then, enable it in your configuration file:

eleventy.config.js

ESM CommonJS

export default function(eleventyConfig) {
	eleventyConfig.setServerOptions({
		module: "@11ty/eleventy-server-browsersync",

		// Default Browsersync options shown:
		port: 8080,
		open: false,
		notify: false,
		ui: false,
		ghostMode: false,

		// Opt-out of the Browsersync snippet
		// snippet: false,
	});
};

module.exports = function(eleventyConfig) {
	eleventyConfig.setServerOptions({
		module: "@11ty/eleventy-server-browsersync",

		// Default Browsersync options shown:
		port: 8080,
		open: false,
		notify: false,
		ui: false,
		ghostMode: false,

		// Opt-out of the Browsersync snippet
		// snippet: false,
	});
};

View the full list of Browsersync options.

`setBrowserSyncConfig`

eleventyConfig.setBrowserSyncConfig was the previous Configuration API method used in versions of Eleventy prior to v2. It was changed to be a no-op in Eleventy v2 (it has no functional purpose).

Eleventy Dev Server Added in v2.0.0

Options

onRequest for request-time processing

Advanced chokidar options

Swap back to Browsersync Added in v2.0.0

setBrowserSyncConfig

Other pages in Watch and Serve:

`onRequest` for request-time processing

Advanced `chokidar` options

`setBrowserSyncConfig`