Add option to configure Webpack Hot Middleware client

Addresses #667

src/Microsoft.AspNetCore.SpaServices/README.md

@@ -633,6 +633,21 @@ Webpack has built-in HMR support for various types of module, such as styles and
 
 This is [documented in detail on the Webpack site](https://webpack.github.io/docs/hot-module-replacement.html). Or to get a working HMR-enabled ASP.NET Core site with Angular 2, React, React+Redux, or Knockout, you can use the [aspnetcore-spa generator](http://blog.stevensanderson.com/2016/05/02/angular2-react-knockout-apps-on-aspnet-core/).
 
+#### Passing options to the Webpack Hot Middleware client
+
+You can configure the [Webpack Hot Middleware client](https://github.com/glenjamin/webpack-hot-middleware#client)
+by modifying your `UseWebpackDevMiddleware` call to include `HotModuleReplacementClientOptions`:
+
+```csharp
+app.UseWebpackDevMiddleware(new WebpackDevMiddlewareOptions {
+    HotModuleReplacement = true,
+    HotModuleReplacementClientOptions = new Dictionary<string, string> { 
+        { "reload", "true" }, 
+    },
+});
+```
+
+**Note**: The `path` option will be ignored, because it is controlled by the `HotModuleReplacementEndpoint` setting.
 
 ## Routing helper: MapSpaFallbackRoute
 

src/Microsoft.AspNetCore.SpaServices/Webpack/WebpackDevMiddlewareOptions.cs

@@ -30,6 +30,11 @@ namespace Microsoft.AspNetCore.SpaServices.Webpack
         /// </summary>
         public bool ReactHotModuleReplacement { get; set; }
 
+        /// <summary> 
+        /// Specifies additional options to be passed to the Webpack Hot Middleware client 
+        /// </summary> 
+        public IDictionary<string, string> HotModuleReplacementClientOptions { get; set; } 
+
         /// <summary>
         /// Specifies the Webpack configuration file to be used. If not set, defaults to 'webpack.config.js'.
         /// </summary>

src/Microsoft.AspNetCore.SpaServices/npm/aspnet-webpack/src/WebpackDevMiddleware.ts

@@ -3,6 +3,7 @@ import * as webpack from 'webpack';
 import * as url from 'url';
 import * as fs from 'fs';
 import * as path from 'path';
+import * as querystring from 'querystring';
 import { requireNewCopy } from './RequireNewCopy';
 
 export type CreateDevServerResult = {
@@ -26,6 +27,7 @@ interface CreateDevServerOptions {
 interface DevServerOptions {
     HotModuleReplacement: boolean;
     HotModuleReplacementServerPort: number;
+    HotModuleReplacementClientOptions: Object;
     ReactHotModuleReplacement: boolean;
 }
 
@@ -37,7 +39,7 @@ interface WebpackConfigFunc {
 }
 type WebpackConfigFileExport = WebpackConfigOrArray | WebpackConfigFunc;
 
-function attachWebpackDevMiddleware(app: any, webpackConfig: webpack.Configuration, enableHotModuleReplacement: boolean, enableReactHotModuleReplacement: boolean, hmrClientEndpoint: string, hmrServerEndpoint: string) {
+function attachWebpackDevMiddleware(app: any, webpackConfig: webpack.Configuration, enableHotModuleReplacement: boolean, enableReactHotModuleReplacement: boolean, hmrClientOptions: HotModuleReplacementClientOptions, hmrClientEndpoint: string, hmrServerEndpoint: string) {
     // Build the final Webpack config based on supplied options
     if (enableHotModuleReplacement) {
         // For this, we only support the key/value config format, not string or string[], since
@@ -53,7 +55,8 @@ function attachWebpackDevMiddleware(app: any, webpackConfig: webpack.Configurati
         // Augment all entry points so they support HMR (unless they already do)
         Object.getOwnPropertyNames(entryPoints).forEach(entryPointName => {
             const webpackHotMiddlewareEntryPoint = 'webpack-hot-middleware/client';
-            const webpackHotMiddlewareOptions = `?path=` + encodeURIComponent(hmrClientEndpoint);
+            hmrClientOptions.path = hmrClientEndpoint;
+            const webpackHotMiddlewareOptions = '?' + querystring.stringify(hmrClientOptions);
             if (typeof entryPoints[entryPointName] === 'string') {
                 entryPoints[entryPointName] = [webpackHotMiddlewareEntryPoint + webpackHotMiddlewareOptions, entryPoints[entryPointName]];
             } else if (firstIndexOfStringStartingWith(entryPoints[entryPointName], webpackHotMiddlewareEntryPoint) < 0) {
@@ -225,6 +228,7 @@ export function createWebpackDevServer(callback: CreateDevServerCallback, option
 
     const enableHotModuleReplacement = options.suppliedOptions.HotModuleReplacement;
     const enableReactHotModuleReplacement = options.suppliedOptions.ReactHotModuleReplacement;
+    const hmrClientOptions = options.suppliedOptions.HotModuleReplacementClientOptions || {};
     if (enableReactHotModuleReplacement && !enableHotModuleReplacement) {
         callback('To use ReactHotModuleReplacement, you must also enable the HotModuleReplacement option.', null);
         return;
@@ -263,7 +267,7 @@ export function createWebpackDevServer(callback: CreateDevServerCallback, option
                         || `http://localhost:${listener.address().port}/__webpack_hmr`; // Fall back on absolute URL to bypass proxying
                     const hmrServerEndpoint = options.hotModuleReplacementEndpointUrl
                         || '/__webpack_hmr';                                            // URL is relative to webpack dev server root
-                    attachWebpackDevMiddleware(app, webpackConfig, enableHotModuleReplacement, enableReactHotModuleReplacement, hmrClientEndpoint, hmrServerEndpoint);
+                    attachWebpackDevMiddleware(app, webpackConfig, enableHotModuleReplacement, enableReactHotModuleReplacement, hmrClientOptions, hmrClientEndpoint, hmrServerEndpoint);
                 }
             });