add comments to tsup config

tsup.config.ts

@@ -3,6 +3,7 @@ import { readFile } from "fs/promises";
 import { globalPackages as globalManagerPackages } from "@storybook/manager/globals";
 import { globalPackages as globalPreviewPackages } from "@storybook/preview/globals";
 
+// The current browsers supported by Storybook v7
 const BROWSER_TARGET: Options['target'] = ["chrome100", "safari15", "firefox91"];
 const NODE_TARGET: Options['target'] = ["node16"];
 
@@ -16,6 +17,15 @@ type BundlerConfig = {
 };
 
 export default defineConfig(async (options) => {
+  // reading the three types of entries from package.json, which has the following structure:
+  // {
+  //  ...
+  //   "bundler": {
+  //     "exportEntries": ["./src/index.ts"],
+  //     "managerEntries": ["./src/manager.ts"],
+  //     "previewEntries": ["./src/preview.ts"]
+  //   }
+  // }
   const packageJson = await readFile('./package.json', 'utf8').then(JSON.parse) as BundlerConfig;
   const {
     bundler: {
@@ -35,6 +45,9 @@ export default defineConfig(async (options) => {
 
   const configs: Options[] = [];
 
+  // export entries are entries meant to be manually imported by the user
+  // they are not meant to be loaded by the manager or preview
+  // they'll be usable in both node and browser environments, depending on which features and modules they depend on
   if (exportEntries.length) {
     configs.push({
       ...commonConfig,
@@ -49,6 +62,9 @@ export default defineConfig(async (options) => {
     });
   }
 
+  // manager entries are entries meant to be loaded into the manager UI
+  // they'll have manager-specific packages externalized and they won't be usable in node
+  // they won't have types generated for them as they're usually loaded automatically by Storybook
   if (managerEntries.length) {
     configs.push({
       ...commonConfig,
@@ -60,6 +76,9 @@ export default defineConfig(async (options) => {
     });
   }
 
+  // preview entries are entries meant to be loaded into the preview iframe
+  // they'll have preview-specific packages externalized and they won't be usable in node
+  // they won't have types generated for them as they're usually loaded automatically by Storybook
   if (previewEntries.length) {
     configs.push({
       ...commonConfig,