marcosmapf · August 10, 2022 14:34 · Aug 10, 2022
diff --git a/federatedApp.ts b/federatedApp.ts
@@ -0,0 +1,64 @@
+type FederatedAppRender = (props?: any) => void
+
+export interface FederatedAppList {
+  [key: string]: () => Promise<FederatedAppRender>
+}
+export interface FederatedApp {
+  render?: FederatedAppRender
+  root: HTMLElement
+}
+
+const handleFederatedApp = (appList?: FederatedAppList) => {
+  const getAppRoot = (appName: string) => {
+    return window[appName]?.root as HTMLElement
+  }
+
+  const setAppRoot = (appName: string, rootElement: HTMLElement) => {
+    if (!window[appName]) {
+      window[appName] = {}
+    }
+
+    window[appName].root = rootElement
+  }
+
+  const isAppInsideShadowRoot = (appName: string) => {
+    return getAppRoot(appName) instanceof ShadowRoot
+  }
+
+  /**
+   * Returns the render function of a Module Federation container
+   * Module federation containers are automatically added to the window object upon module loading.
+   * This module loading occurs if there is an async definition of module (appList) provided to this function or if the module is loaded in any way
+  */
+  const getRenderFederatedApp = async (appName: string, appModule: string): Promise<FederatedAppRender> => {
+    try {
+      const factory = await window[appName]?.get?.(appModule)
+
+      if (factory) {
+        const { default: render } = factory()
+
+        return render
+      }
+
+      const appImportFunction = appList?.[appName]
+
+      if (appImportFunction) {
+        return await appImportFunction()
+      }
+
+      throw new Error(`Missing federated module render function for app: ${appName}`)
+    } catch (error) {
+      const errorMessage = `App ${appName} was not imported correctly, check the module import key or the module entrypoint file.`
+
+      console.error(`${errorMessage} \n\n`, error)
+
+      Promise.reject(error)
+    }
+
+    return Promise.reject(new Error())
+  }
+
+  return { getRenderFederatedApp, getAppRoot, isAppInsideShadowRoot, setAppRoot }
+}
+
+export default handleFederatedApp