Use native in-browser modules and import maps

.changeset/tough-hornets-notice.md

@@ -0,0 +1,6 @@
+---
+"generator-single-spa": major
+"webpack-config-single-spa": major
+---
+
+Use native in-browser modules and import maps rather than SystemJS

packages/generator-single-spa/src/root-config/templates/src/index.ejs

@@ -5,74 +5,45 @@
   <meta name="viewport" content="width=device-width, initial-scale=1.0">
   <meta http-equiv="X-UA-Compatible" content="ie=edge">
   <title>Root Config</title>
-  <!--
-    Remove this if you only support browsers that support async/await.
-    This is needed by babel to share largeish helper code for compiling async/await in older
-    browsers. More information at https://github.com/single-spa/create-single-spa/issues/112
-  -->
-  <script src="https://cdn.jsdelivr.net/npm/regenerator-runtime@0.13.7/runtime.min.js"></script>
   <!--
     This CSP allows any SSL-enabled host and for arbitrary eval(), but you should limit these directives further to increase your app's security.
     Learn more about CSP policies at https://content-security-policy.com/#directive
   -->
   <meta http-equiv="Content-Security-Policy" content="default-src 'self' https: localhost:*; script-src 'unsafe-inline' 'unsafe-eval' https: localhost:*; connect-src https: localhost:* ws://localhost:*; style-src 'unsafe-inline' https:; object-src 'none';">
-  <meta name="importmap-type" content="systemjs-importmap" />
   <!-- If you wish to turn off import-map-overrides for specific environments (prod), uncomment the line below -->
   <!-- More info at https://github.com/joeldenning/import-map-overrides/blob/master/docs/configuration.md#domain-list -->
   <!-- <meta name="import-map-overrides-domains" content="denylist:prod.example.com" /> -->
 
-  <!-- Shared dependencies go into this import map. Your shared dependencies must be of one of the following formats:
-
-    1. System.register (preferred when possible) - https://github.com/systemjs/systemjs/blob/master/docs/system-register.md
-    2. UMD - https://github.com/umdjs/umd
-    3. Global variable
-
-    More information about shared dependencies can be found at https://single-spa.js.org/docs/recommended-setup#sharing-with-import-maps.
-  -->
-  <script type="systemjs-importmap">
-    {
-      "imports": {
-        "single-spa": "https://cdn.jsdelivr.net/npm/single-spa@5.9.0/lib/system/single-spa.min.js"
-      }
-    }
-  </script>
-  <link rel="preload" href="https://cdn.jsdelivr.net/npm/single-spa@5.9.0/lib/system/single-spa.min.js" as="script">
-
-  <!-- Add your organization's prod import map URL to this script's src  -->
-  <!-- <script type="systemjs-importmap" src="/importmap.json"></script> -->
-
   <% if (isLocal) { %>
-  <script type="systemjs-importmap">
+  <script type="overridable-importmap">
     {
       "imports": {
+        "single-spa": "https://cdn.jsdelivr.net/npm/single-spa@5.9.1/lib/system/single-spa.min.js",
         "@<?- orgName ?>/root-config": "//localhost:9000/<?- orgName ?>-root-config.js"
       }
     }
   </script>
+  <% } else { %>
+  <!-- Replace the "src" attribute's value to be the URL of your deployed import map -->
+  <script type="importmap" src="//replace-this-with-your-deployed-import-map-url.js"></script>
   <% } %>
+  <link rel="modulepreload" href="https://cdn.jsdelivr.net/npm/single-spa@5.9.1/lib/system/single-spa.min.js" />
 
   <!--
     If you need to support Angular applications, uncomment the script tag below to ensure only one instance of ZoneJS is loaded
     Learn more about why at https://single-spa.js.org/docs/ecosystem-angular/#zonejs
   -->
   <!-- <script src="https://cdn.jsdelivr.net/npm/zone.js@0.11.3/dist/zone.min.js"></script> -->
 
-  <script src="https://cdn.jsdelivr.net/npm/import-map-overrides@2.2.0/dist/import-map-overrides.js"></script>
-  <% if (isLocal) { %>
-  <script src="https://cdn.jsdelivr.net/npm/systemjs@6.8.3/dist/system.js"></script>
-  <script src="https://cdn.jsdelivr.net/npm/systemjs@6.8.3/dist/extras/amd.js"></script>
-  <% } else { %>
-  <script src="https://cdn.jsdelivr.net/npm/systemjs@6.8.3/dist/system.min.js"></script>
-  <script src="https://cdn.jsdelivr.net/npm/systemjs@6.8.3/dist/extras/amd.min.js"></script>
-  <% } %>
+  <script src="https://cdn.jsdelivr.net/npm/import-map-overrides@3.1.0/dist/import-map-overrides.js"></script>
 </head>
 <body>
   <noscript>
     You need to enable JavaScript to run this app.
   </noscript>
   <main></main>
   <script>
-    System.import('@<?- orgName ?>/root-config');
+    import('@<?- orgName ?>/root-config');
   </script>
   <import-map-overrides-full show-when-local-storage="devtools" dev-libs></import-map-overrides-full>
 </body>

packages/generator-single-spa/src/root-config/templates/src/layout/index.ejs

@@ -6,76 +6,41 @@
   <meta http-equiv="X-UA-Compatible" content="ie=edge">
   <title>Root Config</title>
 
-  <!--
-    Remove this if you only support browsers that support async/await.
-    This is needed by babel to share largeish helper code for compiling async/await in older
-    browsers. More information at https://github.com/single-spa/create-single-spa/issues/112
-  -->
-  <script src="https://cdn.jsdelivr.net/npm/regenerator-runtime@0.13.7/runtime.min.js"></script>
-
   <!--
     This CSP allows any SSL-enabled host and for arbitrary eval(), but you should limit these directives further to increase your app's security.
     Learn more about CSP policies at https://content-security-policy.com/#directive
   -->
   <meta http-equiv="Content-Security-Policy" content="default-src 'self' https: localhost:*; script-src 'unsafe-inline' 'unsafe-eval' https: localhost:*; connect-src https: localhost:* ws://localhost:*; style-src 'unsafe-inline' https:; object-src 'none';">
-  <meta name="importmap-type" content="systemjs-importmap" />
-  <!-- If you wish to turn off import-map-overrides for specific environments (prod), uncomment the line below -->
-  <!-- More info at https://github.com/joeldenning/import-map-overrides/blob/master/docs/configuration.md#domain-list -->
-  <!-- <meta name="import-map-overrides-domains" content="denylist:prod.example.com" /> -->
-
-  <!-- Shared dependencies go into this import map. Your shared dependencies must be of one of the following formats:
-
-    1. System.register (preferred when possible) - https://github.com/systemjs/systemjs/blob/master/docs/system-register.md
-    2. UMD - https://github.com/umdjs/umd
-    3. Global variable
-
-    More information about shared dependencies can be found at https://single-spa.js.org/docs/recommended-setup#sharing-with-import-maps.
-  -->
-  <script type="systemjs-importmap">
-    {
-      "imports": {
-        "single-spa": "https://cdn.jsdelivr.net/npm/single-spa@5.9.0/lib/system/single-spa.min.js"
-      }
-    }
-  </script>
-  <link rel="preload" href="https://cdn.jsdelivr.net/npm/single-spa@5.9.0/lib/system/single-spa.min.js" as="script">
-
-  <!-- Add your organization's prod import map URL to this script's src  -->
-  <!-- <script type="systemjs-importmap" src="/importmap.json"></script> -->
-
   <% if (isLocal) { %>
-  <script type="systemjs-importmap">
+  <script type="overridable-importmap">
     {
       "imports": {
-        "@single-spa/welcome": "https://unpkg.com/single-spa-welcome/dist/single-spa-welcome.js",
+        "single-spa": "https://cdn.jsdelivr.net/npm/single-spa@5.9.1/lib/system/single-spa.min.js",
         "@<?- orgName ?>/root-config": "//localhost:9000/<?- orgName ?>-root-config.js"
       }
     }
   </script>
+  <% } else { %>
+  <!-- Replace the "src" attribute's value to be the URL of your deployed import map -->
+  <script type="importmap" src="//replace-this-with-your-deployed-import-map-url.js"></script>
   <% } %>
+  <link rel="preload" href="https://cdn.jsdelivr.net/npm/single-spa@5.9.1/lib/system/single-spa.min.js" as="script">
 
   <!--
     If you need to support Angular applications, uncomment the script tag below to ensure only one instance of ZoneJS is loaded
     Learn more about why at https://single-spa.js.org/docs/ecosystem-angular/#zonejs
   -->
   <!-- <script src="https://cdn.jsdelivr.net/npm/zone.js@0.11.3/dist/zone.min.js"></script> -->
 
-  <script src="https://cdn.jsdelivr.net/npm/import-map-overrides@2.2.0/dist/import-map-overrides.js"></script>
-  <% if (isLocal) { %>
-  <script src="https://cdn.jsdelivr.net/npm/systemjs@6.8.3/dist/system.js"></script>
-  <script src="https://cdn.jsdelivr.net/npm/systemjs@6.8.3/dist/extras/amd.js"></script>
-  <% } else { %>
-  <script src="https://cdn.jsdelivr.net/npm/systemjs@6.8.3/dist/system.min.js"></script>
-  <script src="https://cdn.jsdelivr.net/npm/systemjs@6.8.3/dist/extras/amd.min.js"></script>
-  <% } %>
+  <script src="https://cdn.jsdelivr.net/npm/import-map-overrides@3.1.0/dist/import-map-overrides.js"></script>
 
 </head>
 <body>
   <noscript>
     You need to enable JavaScript to run this app.
   </noscript>
   <script>
-    System.import('@<?- orgName ?>/root-config');
+    import('@<?- orgName ?>/root-config');
   </script>
   <import-map-overrides-full show-when-local-storage="devtools" dev-libs></import-map-overrides-full>
 </body>

packages/generator-single-spa/src/root-config/templates/src/layout/root-config.ejs

@@ -10,7 +10,7 @@ const routes = constructRoutes(microfrontendLayout);
 const applications = constructApplications({
   routes,
   loadApp({ name }) {
-    return System.import(name);
+    return import(/* webpackIgnore: true */ name);
   },
 });
 const layoutEngine = constructLayoutEngine({ routes, applications });

packages/generator-single-spa/src/root-config/templates/src/root-config.ejs

@@ -3,15 +3,16 @@ import { registerApplication, start<% if (typescript) {%>, LifeCycles<% }%> } fr
 registerApplication({
   name: "@single-spa/welcome",
   app: () =>
-    System.import<% if (typescript) {%><LifeCycles><% } %>(
+    import<% if (typescript) {%><LifeCycles><% } %>(
+      /* webpackIgnore: true */
       "https://unpkg.com/single-spa-welcome/dist/single-spa-welcome.js"
     ),
   activeWhen: ["/"],
 });
 
 // registerApplication({
 //   name: "@<%- orgName %>/navbar",
-//   app: () => System.import("@<%- orgName %>/navbar"),
+//   app: () => import(/* webpackIgnore: true */ "@<%- orgName %>/navbar"),
 //   activeWhen: ["/"]
 // });
 

packages/webpack-config-single-spa/lib/webpack-config-single-spa.js

@@ -2,7 +2,6 @@ const path = require("path");
 const { BundleAnalyzerPlugin } = require("webpack-bundle-analyzer");
 const _HtmlWebpackPlugin = require("html-webpack-plugin");
 const StandaloneSingleSpaPlugin = require("standalone-single-spa-webpack-plugin");
-const SystemJSPublicPathPlugin = require("systemjs-webpack-interop/SystemJSPublicPathWebpackPlugin");
 
 module.exports = webpackConfigSingleSpa;
 
@@ -41,12 +40,17 @@ function webpackConfigSingleSpa(opts) {
     ),
     output: {
       filename: `${opts.orgName}-${opts.projectName}.js`,
-      libraryTarget: "system",
+      library: {
+        type: "module",
+      },
       path: path.resolve(process.cwd(), "dist"),
       uniqueName: opts.projectName,
       devtoolNamespace: `${opts.projectName}`,
       publicPath: "",
     },
+    experiments: {
+      outputModule: true,
+    },
     module: {
       rules: [
         {
@@ -125,10 +129,6 @@ function webpackConfigSingleSpa(opts) {
       new BundleAnalyzerPlugin({
         analyzerMode: webpackConfigEnv.analyze ? "server" : "disabled",
       }),
-      new SystemJSPublicPathPlugin({
-        systemjsModuleName: `@${opts.orgName}/${opts.projectName}`,
-        rootDirectoryLevel: opts.rootDirectoryLevel,
-      }),
       !isProduction && !opts.disableHtmlGeneration && new HtmlWebpackPlugin(),
       !isProduction &&
         !opts.disableHtmlGeneration &&