Register all kernels in one plugin

src/index.ts

@@ -14,86 +14,103 @@ import { IKernel, IKernelSpecs } from '@jupyterlite/kernel';
 import { WebWorkerKernel } from './web_worker_kernel';
 import { IEmpackEnvMetaFile } from './tokens';
 
-function getJson(url: string) {
-  const json_url = URLExt.join(PageConfig.getBaseUrl(), url);
-  const xhr = new XMLHttpRequest();
-  xhr.open('GET', json_url, false);
-  xhr.send(null);
-  return JSON.parse(xhr.responseText);
-}
+/**
+ * Fetches JSON data from the specified URL asynchronously.
+ *
+ * This function constructs the full URL using the base URL from the PageConfig and
+ * the provided relative URL. It then performs a GET request using the Fetch API
+ * and returns the parsed JSON data.
+ *
+ * @param {string} url - The relative URL to fetch the JSON data from.
+ * @returns {Promise<any>} - A promise that resolves to the parsed JSON data.
+ * @throws {Error} - Throws an error if the HTTP request fails.
+ *
+ */
+async function getJson(url: string) {
+  const jsonUrl = URLExt.join(PageConfig.getBaseUrl(), url);
+  const response = await fetch(jsonUrl, { method: 'GET' });
+
+  if (!response.ok) {
+    throw new Error(`HTTP error! status: ${response.status}`);
+  }
 
-let kernel_list: string[] = [];
-try {
-  kernel_list = getJson('xeus/kernels.json');
-} catch (err) {
-  console.log(`Could not fetch xeus/kernels.json: ${err}`);
-  throw err;
+  const data = await response.json();
+  return data;
 }
 
-const plugins = kernel_list.map(
-  (kernel): JupyterLiteServerPlugin<void | IEmpackEnvMetaFile> => {
-    return {
-      id: `@jupyterlite/xeus-${kernel}:register`,
-      autoStart: true,
-      requires: [IKernelSpecs],
-      optional: [
-        IServiceWorkerManager,
-        IBroadcastChannelWrapper,
-        IEmpackEnvMetaFile
-      ],
-      activate: (
-        app: JupyterLiteServer,
-        kernelspecs: IKernelSpecs,
-        serviceWorker?: IServiceWorkerManager,
-        broadcastChannel?: IBroadcastChannelWrapper,
-        empackEnvMetaFile?: IEmpackEnvMetaFile
-      ) => {
-        // Fetch kernel spec
-        const kernelspec = getJson('xeus/kernels/' + kernel + '/kernel.json');
-        kernelspec.name = kernel;
-        kernelspec.dir = kernel;
-        for (const [key, value] of Object.entries(kernelspec.resources)) {
-          kernelspec.resources[key] = URLExt.join(
-            PageConfig.getBaseUrl(),
-            value as string
+const kernelPlugin: JupyterLiteServerPlugin<void> = {
+  id: '@jupyterlite/xeus-kernel:register',
+  autoStart: true,
+  requires: [IKernelSpecs],
+  optional: [
+    IServiceWorkerManager,
+    IBroadcastChannelWrapper,
+    IEmpackEnvMetaFile
+  ],
+  activate: async (
+    app: JupyterLiteServer,
+    kernelspecs: IKernelSpecs,
+    serviceWorker?: IServiceWorkerManager,
+    broadcastChannel?: IBroadcastChannelWrapper,
+    empackEnvMetaFile?: IEmpackEnvMetaFile
+  ) => {
+    // Fetch kernel list
+    let kernelList: string[] = [];
+    try {
+      kernelList = await getJson('xeus/kernels.json');
+    } catch (err) {
+      console.log(`Could not fetch xeus/kernels.json: ${err}`);
+      throw err;
+    }
+    const contentsManager = app.serviceManager.contents;
+
+    for (const kernel of kernelList) {
+      // Fetch kernel spec
+      const kernelspec = await getJson(
+        'xeus/kernels/' + kernel + '/kernel.json'
+      );
+      kernelspec.name = kernel;
+      kernelspec.dir = kernel;
+      for (const [key, value] of Object.entries(kernelspec.resources)) {
+        kernelspec.resources[key] = URLExt.join(
+          PageConfig.getBaseUrl(),
+          value as string
+        );
+      }
+      kernelspecs.register({
+        spec: kernelspec,
+        create: async (options: IKernel.IOptions): Promise<IKernel> => {
+          const mountDrive = !!(
+            (serviceWorker?.enabled && broadcastChannel?.enabled) ||
+            crossOriginIsolated
           );
-        }
 
-        const contentsManager = app.serviceManager.contents;
-        kernelspecs.register({
-          spec: kernelspec,
-          create: async (options: IKernel.IOptions): Promise<IKernel> => {
-            const mountDrive = !!(
-              (serviceWorker?.enabled && broadcastChannel?.enabled) ||
-              crossOriginIsolated
+          if (mountDrive) {
+            console.info(
+              `${kernelspec.name} contents will be synced with Jupyter Contents`
+            );
+          } else {
+            console.warn(
+              `${kernelspec.name} contents will NOT be synced with Jupyter Contents`
             );
-
-            if (mountDrive) {
-              console.info(
-                `${kernelspec.name} contents will be synced with Jupyter Contents`
-              );
-            } else {
-              console.warn(
-                `${kernelspec.name} contents will NOT be synced with Jupyter Contents`
-              );
-            }
-            const link = empackEnvMetaFile
-              ? await empackEnvMetaFile.getLink(kernelspec)
-              : '';
-
-            return new WebWorkerKernel({
-              ...options,
-              contentsManager,
-              mountDrive,
-              kernelSpec: kernelspec,
-              empackEnvMetaLink: link
-            });
           }
-        });
-      }
-    };
+          const link = empackEnvMetaFile
+            ? await empackEnvMetaFile.getLink(kernelspec)
+            : '';
+
+          return new WebWorkerKernel({
+            ...options,
+            contentsManager,
+            mountDrive,
+            kernelSpec: kernelspec,
+            empackEnvMetaLink: link
+          });
+        }
+      });
+    }
+    await app.serviceManager.kernelspecs.refreshSpecs();
   }
-);
+};
 
 const empackEnvMetaPlugin: JupyterLiteServerPlugin<IEmpackEnvMetaFile> = {
   id: '@jupyterlite/xeus:empack-env-meta',
@@ -113,7 +130,5 @@ const empackEnvMetaPlugin: JupyterLiteServerPlugin<IEmpackEnvMetaFile> = {
   }
 };
 
-plugins.push(empackEnvMetaPlugin);
-
-export default plugins;
+export default [empackEnvMetaPlugin, kernelPlugin];
 export { IEmpackEnvMetaFile };