feat(react): Support loading remotes via library: var (#19192)

e2e/react-core/src/react-module-federation.test.ts

@@ -282,6 +282,98 @@ describe('React Module Federation', () => {
     }
   }, 500_000);
 
+  it('should support host and remote with library type var', async () => {
+    const shell = uniq('shell');
+    const remote = uniq('remote');
+
+    runCLI(
+      `generate @nx/react:host ${shell} --remotes=${remote} --project-name-and-root-format=as-provided --no-interactive`
+    );
+
+    // update host and remote to use library type var
+    updateFile(
+      `${shell}/module-federation.config.ts`,
+      stripIndents`
+      import { ModuleFederationConfig } from '@nx/webpack';
+
+      const config: ModuleFederationConfig = {
+        name: '${shell}',
+        library: { type: 'var', name: '${shell}' },
+        remotes: ['${remote}'],
+      };
+
+      export default config;
+      `
+    );
+
+    updateFile(
+      `${shell}/webpack.config.prod.ts`,
+      `export { default } from './webpack.config';`
+    );
+
+    updateFile(
+      `${remote}/module-federation.config.ts`,
+      stripIndents`
+      import { ModuleFederationConfig } from '@nx/webpack';
+
+      const config: ModuleFederationConfig = {
+        name: '${remote}',
+        library: { type: 'var', name: '${remote}' },
+        exposes: {
+          './Module': './src/remote-entry.ts',
+        },
+      };
+
+      export default config;
+      `
+    );
+
+    updateFile(
+      `${remote}/webpack.config.prod.ts`,
+      `export { default } from './webpack.config';`
+    );
+
+    // Update host e2e test to check that the remote works with library type var via navigation
+    updateFile(
+      `${shell}-e2e/src/e2e/app.cy.ts`,
+      `
+    import { getGreeting } from '../support/app.po';
+    
+    describe('${shell}', () => {
+      beforeEach(() => cy.visit('/'));
+    
+      it('should display welcome message', () => {
+        getGreeting().contains('Welcome ${shell}');
+        
+      });
+    
+      it('should navigate to /about from /', () => {
+        cy.get('a').contains('${remote[0].toUpperCase()}${remote.slice(
+        1
+      )}').click();
+        cy.url().should('include', '/${remote}');
+        getGreeting().contains('Welcome ${remote}');
+      });
+    });
+    `
+    );
+
+    // Build host and remote
+    const buildOutput = runCLI(`build ${shell}`);
+    const remoteOutput = runCLI(`build ${remote}`);
+
+    expect(buildOutput).toContain('Successfully ran target build');
+    expect(remoteOutput).toContain('Successfully ran target build');
+
+    if (runE2ETests()) {
+      const hostE2eResults = runCLI(`e2e ${shell}-e2e --no-watch --verbose`);
+      const remoteE2eResults = runCLI(`e2e ${remote}-e2e --no-watch --verbose`);
+
+      expect(hostE2eResults).toContain('All specs passed!');
+      expect(remoteE2eResults).toContain('All specs passed!');
+    }
+  }, 500_000);
+
   function readPort(appName: string): number {
     const config = readJson(join('apps', appName, 'project.json'));
     return config.targets.serve.options.port;

packages/react/src/module-federation/utils.ts

@@ -95,14 +95,26 @@ export async function getModuleFederationConfig(
     projectGraph
   );
 
+  // Choose the correct mapRemotes function based on the server state.
   const mapRemotesFunction = options.isServer ? mapRemotesForSSR : mapRemotes;
-  const determineRemoteUrlFn =
-    options.determineRemoteUrl ||
-    getFunctionDeterminateRemoteUrl(options.isServer);
-  const mappedRemotes =
-    !mfConfig.remotes || mfConfig.remotes.length === 0
-      ? {}
-      : mapRemotesFunction(mfConfig.remotes, 'js', determineRemoteUrlFn);
+
+  // Determine the URL function, either from provided options or by using a default.
+  const determineRemoteUrlFunction = options.determineRemoteUrl
+    ? options.determineRemoteUrl
+    : getFunctionDeterminateRemoteUrl(options.isServer);
+
+  // Map the remotes if they exist, otherwise default to an empty object.
+  let mappedRemotes = {};
+
+  if (mfConfig.remotes && mfConfig.remotes.length > 0) {
+    const isLibraryTypeVar = mfConfig.library?.type === 'var';
+    mappedRemotes = mapRemotesFunction(
+      mfConfig.remotes,
+      'js',
+      determineRemoteUrlFunction,
+      isLibraryTypeVar
+    );
+  }
 
   return { sharedLibraries, sharedDependencies, mappedRemotes };
 }

packages/react/src/module-federation/with-module-federation.ts

@@ -17,6 +17,11 @@ export async function withModuleFederation(
     config.output.uniqueName = options.name;
     config.output.publicPath = 'auto';
 
+    if (options.library?.type === 'var') {
+      config.output.scriptType = 'text/javascript';
+      config.experiments.outputModule = false;
+    }
+
     config.optimization = {
       runtimeChunk: false,
     };
@@ -36,6 +41,13 @@ export async function withModuleFederation(
         shared: {
           ...sharedDependencies,
         },
+        /**
+         * remoteType: 'script' is required for the remote to be loaded as a script tag.
+         * remotes will need to be defined as:
+         *  { appX: 'appX@http://localhost:3001/remoteEntry.js' }
+         *  { appY: 'appY@http://localhost:3002/remoteEntry.js' }
+         */
+        ...(options.library?.type === 'var' ? { remoteType: 'script' } : {}),
       }),
       sharedLibraries.getReplacementPlugin()
     );

packages/webpack/src/utils/module-federation/remotes.ts

@@ -12,29 +12,66 @@ import { extname } from 'path';
 export function mapRemotes(
   remotes: Remotes,
   remoteEntryExt: 'js' | 'mjs',
-  determineRemoteUrl: (remote: string) => string
+  determineRemoteUrl: (remote: string) => string,
+  isRemoteGlobal = false
 ): Record<string, string> {
   const mappedRemotes = {};
 
   for (const remote of remotes) {
     if (Array.isArray(remote)) {
-      const [remoteName, remoteLocation] = remote;
-      const remoteLocationExt = extname(remoteLocation);
-      mappedRemotes[remoteName] = ['.js', '.mjs'].includes(remoteLocationExt)
-        ? remoteLocation
-        : `${
-            remoteLocation.endsWith('/')
-              ? remoteLocation.slice(0, -1)
-              : remoteLocation
-          }/remoteEntry.${remoteEntryExt}`;
+      mappedRemotes[remote[0]] = handleArrayRemote(
+        remote,
+        remoteEntryExt,
+        isRemoteGlobal
+      );
     } else if (typeof remote === 'string') {
-      mappedRemotes[remote] = determineRemoteUrl(remote);
+      mappedRemotes[remote] = handleStringRemote(
+        remote,
+        determineRemoteUrl,
+        isRemoteGlobal
+      );
     }
   }
 
   return mappedRemotes;
 }
 
+// Helper function to deal with remotes that are arrays
+function handleArrayRemote(
+  remote: [string, string],
+  remoteEntryExt: 'js' | 'mjs',
+  isRemoteGlobal: boolean
+): string {
+  const [remoteName, remoteLocation] = remote;
+  const remoteLocationExt = extname(remoteLocation);
+
+  // If remote location already has .js or .mjs extension
+  if (['.js', '.mjs'].includes(remoteLocationExt)) {
+    return remoteLocation;
+  }
+
+  const baseRemote = remoteLocation.endsWith('/')
+    ? remoteLocation.slice(0, -1)
+    : remoteLocation;
+
+  const globalPrefix = isRemoteGlobal
+    ? `${remoteName.replace(/-/g, '_')}@`
+    : '';
+
+  return `${globalPrefix}${baseRemote}/remoteEntry.${remoteEntryExt}`;
+}
+
+// Helper function to deal with remotes that are strings
+function handleStringRemote(
+  remote: string,
+  determineRemoteUrl: (remote: string) => string,
+  isRemoteGlobal: boolean
+): string {
+  const globalPrefix = isRemoteGlobal ? `${remote.replace(/-/g, '_')}@` : '';
+
+  return `${globalPrefix}${determineRemoteUrl(remote)}`;
+}
+
 /**
  * Map remote names to a format that can be understood and used by Module
  * Federation.