Using webpack-dev-server and HMR

Using webpack-dev-server and HMR

While developing, instead of using yarn encore dev --watch, you can use the webpack-dev-server:

$ yarn encore dev-server

This builds and serves the front-end assets from a new server. This server runs at localhost:8080 by default, meaning your build assets are available at localhost:8080/build. This server does not actually write the files to disk; instead it serves them from memory, allowing for hot module reloading.

As a consequence, the link and script tags need to point to the new server. If you’re using the encore_entry_script_tags() and encore_entry_link_tags() Twig shortcuts (or are processing your assets through entrypoints.json in some other way), you’re done: the paths in your templates will automatically point to the dev server.

The dev-server command supports all the options defined by webpack-dev-server. You can set these options via command line options:

$ yarn encore dev-server --https --port 9000

You can also set these options using the Encore.configureDevServerOptions() method in your webpack.config.js file:

// webpack.config.js
// ...
Encore
    // ...
    .configureDevServerOptions(options => {
        options.https = {
            key: '/path/to/server.key',
            cert: '/path/to/server.crt',
        }
    })
;

New in version 0.28.4: The Encore.configureDevServerOptions() method was introduced in Encore 0.28.4.

Hot Module Replacement HMR

Encore does support HMR for Vue.js, but does not work for styles anywhere at this time. To activate it, pass the --hot option:

$ ./node_modules/.bin/encore dev-server --hot

If you want to use SSL with self-signed certificates, add the --https, --pfx=, and --allowed-hosts options to the dev-server command in the package.json file:

  {
      ...
      "scripts": {
-        "dev-server": "encore dev-server",
+        "dev-server": "encore dev-server --https --pfx=$HOME/.symfony/certs/default.p12 --allowed-hosts=mydomain.wip",
          ...
      }
  }

If you experience issues related to CORS (Cross Origin Resource Sharing), add the --disable-host-check and --port options to the dev-server command in the package.json file:

  {
      ...
      "scripts": {
-        "dev-server": "encore dev-server",
+        "dev-server": "encore dev-server --port 8080 --disable-host-check",
          ...
      }
  }

Caution

Beware that it’s not recommended to disable host checking in general, but here it’s required to solve the CORS issue.

This work, including the code samples, is licensed under a Creative Commons BY-SA 3.0 license.