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webpack-dev-middleware

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webpack-dev-middleware

An express-style development middleware for use with webpack bundles and allows for serving of the files emitted from webpack. This should be used for development only.

Some of the benefits of using this middleware include:

  • No files are written to disk, rather it handles files in memory
  • If files changed in watch mode, the middleware delays requests until compiling has completed.
  • Supports hot module reload (HMR).

Getting Started

First thing's first, install the module:

npm install webpack-dev-middleware --save-dev

We do not recommend installing this module globally.

Usage

const express = require("express");
const webpack = require("webpack");
const middleware = require("webpack-dev-middleware");

const compiler = webpack({
  // webpack options
});

const app = express();

app.use(
  middleware(compiler, {
    // webpack-dev-middleware options
  }),
);

app.listen(3000, () => console.log("Example app listening on port 3000!"));

See below for an example of use with fastify.

Options

Name Type Default Description
methods Array [ 'GET', 'HEAD' ] Allows to pass the list of HTTP request methods accepted by the middleware
headers Array|Object|Function undefined Allows to pass custom HTTP headers on each request.
index boolean|string index.html If false (but not undefined), the server will not respond to requests to the root URL.
mimeTypes Object undefined Allows to register custom mime types or extension mappings.
mimeTypeDefault string undefined Allows to register a default mime type when we can't determine the content type.
etag boolean| "weak"| "strong" undefined Enable or disable etag generation.
lastModified boolean undefined Enable or disable Last-Modified header. Uses the file system's last modified value.
cacheControl boolean|number|string|Object undefined Enable or disable setting Cache-Control response header.
cacheImmutable boolean undefined Enable or disable setting Cache-Control: public, max-age=31536000, immutable response header for immutable assets.
publicPath string undefined The public path that the middleware is bound to.
stats boolean|string|Object stats (from a configuration) Stats options object or preset name.
serverSideRender boolean undefined Instructs the module to enable or disable the server-side rendering mode.
writeToDisk boolean|Function false Instructs the module to write files to the configured location on disk as specified in your webpack configuration.
outputFileSystem Object memfs Set the default file system which will be used by webpack as primary destination of generated files.
modifyResponseData Function undefined Allows to set up a callback to change the response data.
hot boolean|Object false Enables a Server-Sent Events endpoint that drives the browser HMR client.
forwardError boolean false Enable or disable forwarding errors to the next middleware.

The middleware accepts an options Object. The following is a property reference for the Object.

methods

Type: Array
Default: [ 'GET', 'HEAD' ]

This property allows a user to pass the list of HTTP request methods accepted by the middleware**.

headers

Type: Array|Object|Function Default: undefined

This property allows a user to pass custom HTTP headers on each request. eg. { "X-Custom-Header": "yes" }

or

webpackDevMiddleware(compiler, {
  headers: () => ({
    "Last-Modified": new Date(),
  }),
});

or

webpackDevMiddleware(compiler, {
  headers: (req, res, context) => {
    res.setHeader("Last-Modified", new Date());
  },
});

or

webpackDevMiddleware(compiler, {
  headers: [
    {
      key: "X-custom-header",
      value: "foo",
    },
    {
      key: "Y-custom-header",
      value: "bar",
    },
  ],
});

or

webpackDevMiddleware(compiler, {
  headers: () => [
    {
      key: "X-custom-header",
      value: "foo",
    },
    {
      key: "Y-custom-header",
      value: "bar",
    },
  ],
});
index

Type: Boolean|String Default: index.html

If false (but not undefined), the server will not respond to requests to the root URL.

mimeTypes

Type: Object
Default: undefined

This property allows a user to register custom mime types or extension mappings. eg. mimeTypes: { phtml: 'text/html' }.

Please see the documentation for mime-types for more information.

mimeTypeDefault

Type: String
Default: undefined

This property allows a user to register a default mime type when we can't determine the content type.

etag

Type: "weak" | "strong"
Default: undefined

Enable or disable etag generation. Boolean value use

lastModified

Type: Boolean Default: undefined

Enable or disable Last-Modified header. Uses the file system's last modified value.

cacheControl

Type: Boolean | Number | String | { maxAge?: number, immutable?: boolean } Default: undefined

Depending on the setting, the following headers will be generated:

  • Boolean - Cache-Control: public, max-age=31536000000
  • Number - Cache-Control: public, max-age=YOUR_NUMBER
  • String - Cache-Control: YOUR_STRING
  • { maxAge?: number, immutable?: boolean } - Cache-Control: public, max-age=YOUR_MAX_AGE_or_31536000000, also , immutable can be added if you set the immutable option to true

Enable or disable setting Cache-Control response header.

cacheImmutable

Type: Boolean Default: undefined

Enable or disable setting Cache-Control: public, max-age=31536000, immutable response header for immutable assets (i.e. asset with a hash like image.a4c12bde.jpg). Immutable assets are assets that have their hash in the file name therefore they can be cached, because if you change their contents the file name will be changed. Take preference over the cacheControl option if the asset was defined as immutable.

publicPath

Type: String Default: output.publicPath (from a configuration)

The public path that the middleware is bound to.

Best Practice: use the same publicPath defined in your webpack config. For more information about publicPath, please see the webpack documentation.

stats

Type: Boolean|String|Object Default: stats (from a configuration)

Stats options object or preset name.

serverSideRender

Type: Boolean
Default: undefined

Instructs the module to enable or disable the server-side rendering mode. Please see Server-Side Rendering for more information.

writeToDisk

Type: Boolean|Function
Default: false

If true, the option will instruct the module to write files to the configured location on disk as specified in your webpack config file. Setting writeToDisk: true won't change the behavior of the webpack-dev-middleware, and bundle files accessed through the browser will still be served from memory. This option provides the same capabilities as the WriteFilePlugin.

This option also accepts a Function value, which can be used to filter which files are written to disk. The function follows the same premise as Array#filter in which a return value of false will not write the file, and a return value of true will write the file to disk. eg.

const webpack = require("webpack");

const configuration = {/* Webpack configuration */};
const compiler = webpack(configuration);

middleware(compiler, {
  writeToDisk: (filePath) => /superman\.css$/.test(filePath),
});
outputFileSystem

Type: Object
Default: memfs

Set the default file system which will be used by webpack as primary destination of generated files. This option isn't affected by the writeToDisk option.

You have to provide .join() and mkdirp method to the outputFileSystem instance manually for compatibility with webpack@4.

This can be done simply by using path.join:

const path = require("node:path");
const mkdirp = require("mkdirp");
const myOutputFileSystem = require("my-fs");
const webpack = require("webpack");

myOutputFileSystem.join = path.join.bind(path); // no need to bind
myOutputFileSystem.mkdirp = mkdirp.bind(mkdirp); // no need to bind

const compiler = webpack({/* Webpack configuration */});

middleware(compiler, { outputFileSystem: myOutputFileSystem });
modifyResponseData

Allows to set up a callback to change the response data.

const webpack = require("webpack");

const configuration = {/* Webpack configuration */};
const compiler = webpack(configuration);

middleware(compiler, {
  // Note - if you send the `Range` header you will have `ReadStream`
  // Also `data` can be `string` or `Buffer`
  modifyResponseData: (req, res, data, byteLength) =>
    // Your logic
    // Don't use `res.end()` or `res.send()` here
    ({ data, byteLength }),
});
hot

Type: Boolean | Object Default: false

Enables hot module replacement by serving a Server-Sent Events endpoint that publishes the webpack compiler's building, built and sync events to connected clients. Whether those events carry errors and warnings follows the stats option, so one setting governs what a build reports in the terminal and in the browser — stats: "errors-only" keeps warnings out of both, and stats: false keeps both out. When true, defaults are used; pass an object to customise. Use this option together with the browser runtime shipped as webpack-dev-middleware/client.

const webpack = require("webpack");

const compiler = webpack({
  /* Webpack configuration with HotModuleReplacementPlugin and the client entry */
});

middleware(compiler, { hot: true });

The object form accepts these options:

Name Type Default Description
path string '/__webpack_hmr' Path the SSE endpoint is served at.
heartbeat number 10000 Interval (in milliseconds) between keep-alive frames.
progress boolean false Publish compilation progress events to the clients.
statsOptions object undefined Deprecated — do not use; see stats.
hot.path

Type: String Default: '/__webpack_hmr'

Path the SSE endpoint is served at. Must start with a slash and match the path option used by the client.

hot.heartbeat

Type: Number Default: 10000

Heartbeat interval (in milliseconds) used to keep the SSE connection alive when no compilation events are produced. Must be 1 or greater.

hot.progress

Type: Boolean Default: false

Publish compilation progress events ({ action: "progress", percent, message }) to the clients using webpack's ProgressPlugin. The bundled client shows the percentage in its building badge (see the client progress option).

hot.statsOptions

Deprecated, and removed in the next major release. Do not use it.

Use these instead:

To Use
decide what a build reports, in the terminal and in the payload stats
quiet the browser console alone the client's logging
hide problems from the overlay alone the client's overlay
drop a warning everywhere at once webpack's ignoreWarnings

Values still passed here apply until the option is removed, except hash, timings and children, which are ignored: the client compares hash against its own bundle's to decide whether an update applies, timings carries the build time it reports, and children would replace the bundle's hash with a child compilation's, so a page would reload instead of updating.

Hot Module Replacement client

When the server is configured to serve the hot module replacement endpoint, the bundled application needs a small runtime that subscribes to that stream and applies the updates. webpack-dev-middleware ships that runtime under the ./client subpath. Add it as a webpack entry next to your application code and enable HotModuleReplacementPlugin:

const webpack = require("webpack");

module.exports = {
  entry: ["webpack-dev-middleware/client", "./src/app.js"],
  plugins: [new webpack.HotModuleReplacementPlugin()],
};

The runtime connects to /__webpack_hmr by default. Any of the options below can be set by adding a query string to the entry path:

entry: [
  "webpack-dev-middleware/client?reload=false&overlay=false",
  "./src/app.js",
];

The runtime ships as ES5 and uses no built-in newer than ES5, apart from EventSource and Promise (which HMR itself needs), so it runs in old browsers too — set target to ["web", "es5"] in your configuration so webpack emits its own runtime as ES5 as well.

Client options
Name Type Default Description
path string /__webpack_hmr Path the SSE endpoint is served at. Must match the server hot.path.
timeout number 20000 Reconnection / heartbeat watchdog timeout in milliseconds.
overlay boolean|Object true In-page overlay for problems: a boolean, or a JSON object — see overlay options. Same value shape as webpack-dev-server's client.overlay, plus a few webpack-dev-middleware extensions.
reload boolean true Fall back to a full page reload when an update cannot be applied through HMR (e.g. recovering from a broken build). Enabled by default, unlike webpack-hot-middleware; set to false to keep HMR-only.
logging string "info" Logger level — one of "none", "error", "warn", "info", "log", "verbose". Uses webpack's runtime logger.
name string "" Restrict updates to a specific compilation name (useful with multi-compiler).
autoConnect boolean true Connect on load; set to false and call setOptionsAndConnect() manually.
progress boolean true Show a small badge in the page while a rebuild is in progress (with the compilation percentage when the server enables hot.progress). Set to false to disable.
dynamicPublicPath boolean false Prefix path with __webpack_public_path__ at runtime. The leading slash of path is stripped and no other normalization is applied, so the public path should end with /.
Client overlay options

Passed as a JSON object, e.g. ?overlay={"warnings":false}. The three problem kinds default to true when the object leaves them out; a filter function (URI-encoded) shows only the messages it accepts.

Name Type Default Description
errors boolean|Function true Show build errors.
warnings boolean|Function true Show build warnings.
runtimeErrors boolean|Function true Show uncaught runtime errors and unhandled rejections.
trustedTypesPolicyName string undefined Trusted Types policy name used for the overlay's HTML.
styles Object undefined webpack-dev-middleware extension: CSS overrides for the overlay card (element.style keys).
ansiColors Object undefined webpack-dev-middleware extension: ANSI → HTML color map, as in ansi-html-community.
openEditorEndpoint string "" webpack-dev-middleware extension: when set, file references become clickable and issue GET <endpoint>?fileName=<file:line:column>; your server provides it, e.g. a route calling launch-editor.
paginate boolean true webpack-dev-middleware extension: show one problem at a time with prev/next navigation.
Programmatic API

webpack-dev-middleware/client also exports a few functions for advanced cases:

const hotClient = require("webpack-dev-middleware/client");

// Receive every HMR payload (building / built / sync / custom).
hotClient.subscribeAll((payload) => {
  console.log("hot event", payload);
});

// Receive payloads whose `action` is not recognised by the client (i.e. custom
// payloads published via the server's `instance.context.hot.publish(...)`).
hotClient.subscribe((payload) => {
  // do something
});

// Replace the default error overlay with your own implementation.
hotClient.useCustomOverlay({
  showProblems(type, lines) {
    /* ... */
  },
  clear() {
    /* ... */
  },
});

// Connect manually when `autoConnect=false`. Accepts the same option keys as
// the query-string API above.
hotClient.setOptionsAndConnect({ path: "/__hmr" });

// Close the SSE connection and stop reconnecting (e.g. before tearing the
// page down). A later `setOptionsAndConnect` call opens a fresh connection.
hotClient.disconnect();

The error overlay is also exposed as a standalone module so other tooling (e.g. webpack-dev-server) can reuse it without the SSE client:

import configureOverlay, {
  clear,
  showProblems,
} from "webpack-dev-middleware/client/overlay";

const overlay = configureOverlay({
  // ansiColors, overlayStyles, trustedTypesPolicyName, catchRuntimeError,
  // openEditorEndpoint, paginate
});

overlay.showProblems("errors", ["Something broke"]);
overlay.clear();

The overlay state is a per-page singleton: every bundled copy of the module renders into the same overlay. Multiple clients can report side by side by passing a source — each source keeps its own slot and the overlay shows the union, with errors from any source taking precedence over warnings:

overlay.showProblems("errors", ["Something broke"], "my-client");
// Drop only this client's problems; other sources stay on screen.
overlay.clear("my-client");
// Without a source, everything is dismissed (same as Esc / backdrop / ×).
overlay.clear();

The building indicator is exposed the same way:

import { hide, show } from "webpack-dev-middleware/client/indicator";

show("Rebuilding…"); // pulsing dot
show("Rebuilding… 42%", 42); // progress ring
hide();

The badge is a per-page singleton shared by every bundled copy of the module. Concurrent builds can report through a source — the badge stays until every source finished:

show("Rebuilding app…", undefined, "app");
show("Rebuilding admin…", undefined, "admin");
hide("app"); // still shown — "admin" is building
hide("admin"); // removed
hide(); // without a source: removed unconditionally

Migrating from webpack-hot-middleware

The hot option replaces webpack-hot-middleware: one middleware serves the assets and the SSE endpoint, and the client runtime ships under webpack-dev-middleware/client. The endpoint (/__webpack_hmr) and its Server-Sent Events transport are unchanged, so the browser reaches the new server the same way; the payloads, option names and a few defaults need a look.

See migration-from-webpack-hot-middleware.md — it walks the whole move: prerequisites, the server and webpack-configuration changes, every option mapped, the behavior differences worth knowing, the other frameworks, troubleshooting, and a checklist.

HMR notes and troubleshooting

Browser connection limits (many tabs)

Each open tab keeps one SSE connection to the hot.path endpoint. Over HTTP/1.1, browsers allow only ~6 concurrent connections per origin, so opening many tabs can leave the extra ones hanging (browsers have marked this Won't Fix). Multiple webpack entries on the same page already share a single connection, and the endpoint works over HTTP/2 out of the box — serve your development server over HTTP/2 if you need many simultaneous tabs.

Filtering warnings

Three layers, from build to presentation:

  • webpack's ignoreWarnings removes them from the stats, so nothing reports them anywhere.
  • The middleware's stats option decides what a build reports, in the terminal and in the SSE payload alike: stats: "errors-only" keeps warnings out of both.
  • On the client, ?overlay={"warnings":false} hides them from the overlay and ?logging=error from the console, per page rather than per server.
Paths and public paths
  • The client path option accepts absolute URLs (the endpoint sends Access-Control-Allow-Origin: *), which allows connecting across ports or hosts. Pages served over HTTPS need the endpoint over HTTPS too.
  • For apps with nested routes (/some/route), use an absolute output.publicPath (e.g. "/"): with a relative one the browser resolves *.hot-update.json requests against the current route and they 404.
Custom events

The server can broadcast arbitrary payloads and the client can react to them — for example, forcing every open tab to reload on demand:

// Server
const instance = middleware(compiler, { hot: true });
instance.context.hot.publish({ action: "reload-all" });
// Client
const hotClient = require("webpack-dev-middleware/client");

hotClient.subscribe((payload) => {
  if (payload.action === "reload-all") {
    globalThis.location.reload();
  }
});

API

webpack-dev-middleware also provides convenience methods that can be use to interact with the middleware at runtime:

close(callback)

Instructs webpack-dev-middleware instance to stop watching for file changes.

Parameters
callback

Type: Function Required: No

A function executed once the middleware has stopped watching.

const express = require("express");
const webpack = require("webpack");

const compiler = webpack({/* Webpack configuration */});

const middleware = require("webpack-dev-middleware");

const instance = middleware(compiler);

// eslint-disable-next-line new-cap
const app = new express();

app.use(instance);

setTimeout(() => {
  // Says `webpack` to stop watch changes
  instance.close();
}, 1000);
invalidate(callback)

Instructs webpack-dev-middleware instance to recompile the bundle, e.g. after a change to the configuration.

Parameters
callback

Type: Function Required: No

A function executed once the middleware has invalidated.

const express = require("express");
const webpack = require("webpack");

const compiler = webpack({/* Webpack configuration */});

const middleware = require("webpack-dev-middleware");

const instance = middleware(compiler);

// eslint-disable-next-line new-cap
const app = new express();

app.use(instance);

setTimeout(() => {
  // After a short delay the configuration is changed and a banner plugin is added to the config
  new webpack.BannerPlugin("A new banner").apply(compiler);

  // Recompile the bundle with the banner plugin:
  instance.invalidate();
}, 1000);
waitUntilValid(callback)

Executes a callback function when the compiler bundle is valid, typically after compilation.

Parameters
callback

Type: Function Required: No

A function executed when the bundle becomes valid. If the bundle is valid at the time of calling, the callback is executed immediately.

const express = require("express");
const webpack = require("webpack");

const compiler = webpack({/* Webpack configuration */});

const middleware = require("webpack-dev-middleware");

const instance = middleware(compiler);

// eslint-disable-next-line new-cap
const app = new express();

app.use(instance);

instance.waitUntilValid(() => {
  console.log("Package is in a valid state");
});
getFilenameFromUrl(url)

Get filename from URL.

Parameters
url

Type: String Required: Yes

URL for the requested file.

const express = require("express");
const webpack = require("webpack");

const compiler = webpack({/* Webpack configuration */});

const middleware = require("webpack-dev-middleware");

const instance = middleware(compiler);

// eslint-disable-next-line new-cap
const app = new express();

app.use(instance);

instance.waitUntilValid(() => {
  instance
    .getFilenameFromUrl("/bundle.js")
    .then((filename) => {
      if (!filename) {
        return;
      }

      console.log(`Filename is ${filename}`);
    })
    .catch((err) => {
      console.log(`Error: ${err}`);
    });
});
plugin(compiler, options)

Creates middleware instance in plugin mode.

In plugin mode, stats output is written through custom code (i.e. in callback for watch or where you are calling stats.toString(options)) instead of console.log. In this case, the stats option is not supported because webpack-dev-middleware does not have access to the code where the stats will be output. You will also need to manually run the watch method.

Why do you need this mode? In some cases, you may want to have multiple dev servers or run only one dev server when you have multiple configurations, and this is suitable for you.

const webpack = require("webpack");
const middleware = require("webpack-dev-middleware");

const compiler = webpack({
  plugins: [
    {
      apply(compiler) {
        const devMiddleware = middleware(
          compiler,
          {/* webpack-dev-middleware options */},
          true,
        );
      },
    },
  ],
  /* Webpack configuration */
});

compiler.watch((err, stats) => {
  if (err) {
    console.error(err);
    return;
  }

  console.log(stats.toString());
});
Plugin wrappers

The following wrappers enable plugin mode for framework integrations:

  • middleware(compiler, options, true) (connect/express like middleware)
  • middleware.koaWrapper(compiler, options, true)
  • middleware.hapiWrapper(true)
  • middleware.honoWrapper(compiler, options, true)

They are equivalent to koaWrapper/hapiWrapper/honoWrapper, but use plugin mode logging behavior.

forwardError

Type: boolean Default: false

Enable or disable forwarding errors to the next middleware. If true, errors will be forwarded to the next middleware, otherwise, they will be handled by webpack-dev-middleware and a response will be handled case by case.

This option don't work with hono, koa and hapi, because of the differences in error handling between these frameworks and express.

const express = require("express");
const webpack = require("webpack");
const middleware = require("webpack-dev-middleware");

const compiler = webpack({/* Webpack configuration */});

const instance = middleware(compiler, { forwardError: true });

const app = express();
app.use(instance);

app.use((err, req, res, next) => {
  console.log(`Error: ${err}`);
  res.status(500).send("Something broke!");
});

FAQ

Avoid blocking requests to non-webpack resources.

Since output.publicPath and output.filename/output.chunkFilename can be dynamic, it's not possible to know which files are webpack bundles (and they public paths) and which are not, so we can't avoid blocking requests.

But there is a solution to avoid it - mount the middleware to a non-root route, for example:

const express = require("express");
const webpack = require("webpack");
const middleware = require("webpack-dev-middleware");

const compiler = webpack({
  // webpack options
});

const app = express();

// Mounting the middleware to the non-root route allows avoids this.
// Note - check your public path, if you want to handle `/dist/`, you need to setup `output.publicPath` to `/` value.
app.use(
  "/dist/",
  middleware(compiler, {
    // webpack-dev-middleware options
  }),
);

app.listen(3000, () => console.log("Example app listening on port 3000!"));

Server-Side Rendering

Note: this feature is experimental and may be removed or changed completely in the future.

In order to develop an app using server-side rendering, we need access to the stats, which is generated with each build.

With server-side rendering enabled, webpack-dev-middleware sets the stats to res.locals.webpack.devMiddleware.stats and the filesystem to res.locals.webpack.devMiddleware.outputFileSystem before invoking the next middleware, allowing a developer to render the page body and manage the response to clients.

Note: Requests for bundle files will still be handled by webpack-dev-middleware and all requests will be pending until the build process is finished with server-side rendering enabled.

Example Implementation:

const express = require("express");
const isObject = require("is-object");
const webpack = require("webpack");
const middleware = require("webpack-dev-middleware");

const compiler = webpack({/* Webpack configuration */});

// eslint-disable-next-line new-cap
const app = new express();

// This function makes server rendering of asset references consistent with different webpack chunk/entry configurations
function normalizeAssets(assets) {
  if (isObject(assets)) {
    return Object.values(assets);
  }

  return Array.isArray(assets) ? assets : [assets];
}

app.use(middleware(compiler, { serverSideRender: true }));

// The following middleware would not be invoked until the latest build is finished.
app.use((req, res) => {
  const { devMiddleware } = res.locals.webpack;
  const { outputFileSystem } = devMiddleware;
  const jsonWebpackStats = devMiddleware.stats.toJson();
  const { assetsByChunkName, outputPath } = jsonWebpackStats;

  // Then use `assetsByChunkName` for server-side rendering
  // For example, if you have only one main chunk:
  res.send(`
<html>
  <head>
    <title>My App</title>
    <style>
    ${normalizeAssets(assetsByChunkName.main)
      .filter((path) => path.endsWith(".css"))
      .map((path) => outputFileSystem.readFileSync(path.join(outputPath, path)))
      .join("\n")}
    </style>
  </head>
  <body>
    <div id="root"></div>
    ${normalizeAssets(assetsByChunkName.main)
      .filter((path) => path.endsWith(".js"))
      .map((path) => `<script src="${path}"></script>`)
      .join("\n")}
  </body>
</html>
  `);
});

Support

We do our best to keep Issues in the repository focused on bugs, features, and needed modifications to the code for the module. Because of that, we ask users with general support, "how-to", or "why isn't this working" questions to try one of the other support channels that are available.

Your first-stop-shop for support for webpack-dev-server should by the excellent documentation for the module. If you see an opportunity for improvement of those docs, please head over to the webpack.js.org repo and open a pull request.

From there, we encourage users to visit the webpack discussions and talk to the fine folks there. If your quest for answers comes up dry in chat, head over to StackOverflow and do a quick search or open a new question. Remember; It's always much easier to answer questions that include your webpack.config.js and relevant files!

If you're twitter-savvy you can tweet #webpack with your question and someone should be able to reach out and lend a hand.

If you have discovered a , have a feature suggestion, or would like to see a modification, please feel free to create an issue on Github. Note: The issue template isn't optional, so please be sure not to remove it, and please fill it out completely.

Other servers

Examples of use with other servers will follow here.

Connect
const http = require("node:http");
const connect = require("connect");
const webpack = require("webpack");
const devMiddleware = require("webpack-dev-middleware");
const webpackConfig = require("./webpack.config.js");

const compiler = webpack(webpackConfig);
const devMiddlewareOptions = {/** Your webpack-dev-middleware-options */};
const app = connect();

app.use(devMiddleware(compiler, devMiddlewareOptions));

http.createServer(app).listen(3000);
Router
const http = require("node:http");
const finalhandler = require("finalhandler");
const Router = require("router");
const webpack = require("webpack");
const devMiddleware = require("webpack-dev-middleware");
const webpackConfig = require("./webpack.config.js");

const compiler = webpack(webpackConfig);
const devMiddlewareOptions = {/** Your webpack-dev-middleware-options */};

// eslint-disable-next-line new-cap
const router = Router();

router.use(devMiddleware(compiler, devMiddlewareOptions));

const server = http.createServer((req, res) => {
  router(req, res, finalhandler(req, res));
});

server.listen(3000);
Express
const express = require("express");
const webpack = require("webpack");
const devMiddleware = require("webpack-dev-middleware");
const webpackConfig = require("./webpack.config.js");

const compiler = webpack(webpackConfig);
const devMiddlewareOptions = {/** Your webpack-dev-middleware-options */};
const app = express();

app.use(devMiddleware(compiler, devMiddlewareOptions));

app.listen(3000, () => console.log("Example app listening on port 3000!"));
Koa
const Koa = require("koa");
const webpack = require("webpack");
const middleware = require("webpack-dev-middleware");
const webpackConfig = require("./webpack.simple.config");

const compiler = webpack(webpackConfig);
const devMiddlewareOptions = {/** Your webpack-dev-middleware-options */};
const app = new Koa();

app.use(middleware.koaWrapper(compiler, devMiddlewareOptions));
// Alternative usage (when you want to use as a plugin, i.e. all stats will be printed by other code):
// app.use(middleware.koaWrapper(compiler, devMiddlewareOptions, true));

app.listen(3000);
Hapi
const Hapi = require("@hapi/hapi");
const webpack = require("webpack");
const devMiddleware = require("webpack-dev-middleware");
const webpackConfig = require("./webpack.config.js");

const compiler = webpack(webpackConfig);
const devMiddlewareOptions = {};

const server = Hapi.server({ port: 3000, host: "localhost" });

await server.register({
  plugin: devMiddleware.hapiWrapper(),
  options: {
    // The `compiler` option is required
    compiler,
    ...devMiddlewareOptions,
  },
});

// Alternative usage (when you want to use as a plugin, i.e. all stats will be printed by other code):
// await server.register({
//   plugin: devMiddleware.hapiWrapper(true),
//   options: {
//     // The `compiler` option is required
//     compiler,
//     ...devMiddlewareOptions,
//   },
// });

await server.start();

console.log("Server running on %s", server.info.uri);

process.on("unhandledRejection", (err) => {
  console.log(err);
  process.exit(1);
});
Fastify

Fastify interop will require the use of fastify-express instead of middie for providing middleware support. As the authors of fastify-express recommend, this should only be used as a stopgap while full Fastify support is worked on.

const fastify = require("fastify")();
const webpack = require("webpack");
const devMiddleware = require("webpack-dev-middleware");
const webpackConfig = require("./webpack.config.js");

const compiler = webpack(webpackConfig);
const devMiddlewareOptions = {/** Your webpack-dev-middleware-options */};

await fastify.register(require("@fastify/express"));
await fastify.use(devMiddleware(compiler, devMiddlewareOptions));
await fastify.listen(3000);
Hono
import { serve } from "@hono/node-server";
import { Hono } from "hono";
import webpack from "webpack";
import devMiddleware from "webpack-dev-middleware";
import webpackConfig from "./webpack.config.js";

const compiler = webpack(webpackConfig);
const devMiddlewareOptions = {/** Your webpack-dev-middleware-options */};

const app = new Hono();

app.use(devMiddleware.honoWrapper(compiler, devMiddlewareOptions));

// Alternative usage (when you want to use as a plugin, i.e. all stats will be printed by other code):
// const honoDevMiddleware = devMiddleware.honoWrapper(compiler, devMiddlewareOptions, true)

serve(app);

Contributing

Please take a moment to read our contributing guidelines if you haven't yet done so.

CONTRIBUTING

License

MIT

Keywords

webpackmiddlewaredevelopment