add support for custom named exports (#452)

docs/05-configuration.md

@@ -93,11 +93,15 @@ $ snowpack dev --no-bundle
 - **`alias`** | `{[mapFromPackageName: string]: string}`
   - Alias an installed package name. This applies to imports within your application and within your installed dependency graph. 
   - Example: `"alias": {"react": "preact/compat", "react-dom": "preact/compat"}`
+- **`namedExports`** | `string[]` 
+  - Legacy Common.js (CJS) packages should only be imported by the default import (Example: `import reactTable from 'react-table'`)
+  - But, some packages use named exports in their documentation, which can cause confusion for users. (Example: `import {useTable} from 'react-table'`)
+  - You can enable "fake/synthetic" named exports for Common.js package by adding the package name under this configuration.
+  - Example: `"namedExports": ["react-table"]`
 - **`rollup`**
   - Snowpack uses Rollup internally to install your packages. This `rollup` config option gives you deeper control over the internal rollup configuration that we use. 
   - **`rollup.plugins`** - Specify [Custom Rollup plugins](#installing-non-js-packages) if you are dealing with non-standard files.
   - **`rollup.dedupe`** - If needed, deduplicate multiple versions/copies of a packages to a single one. This helps prevent issues with some packages when multiple versions are installed from your node_modules tree. See [rollup-plugin-node-resolve](https://github.com/rollup/plugins/tree/master/packages/node-resolve#usage) for more documentation.
-  - **`rollup.namedExports`** - **DEPRECATED** Rollup has gotten good enough at Common.js<->ESM interop that it no longer needs this fallback, and will fail if you pass it. If you're currently using it, it should be safe to remove.
 
 #### Dev Options
 

src/commands/install.ts

@@ -48,14 +48,16 @@ class ErrorWithHint extends Error {
 //   import React from 'react';
 // But, some large projects use named exports in their documentation:
 //   import {useState} from 'react';
-// Note that this is not a problem for ESM packages, only CJS.
+//
+// We use "/index.js here to match the official package, but not any ESM aliase packages
+// that the user may have installed instead (ex: react-esm).
 const CJS_PACKAGES_TO_AUTO_DETECT = [
   'react/index.js',
   'react-dom/index.js',
-  'react-table/index.js',
   'react-is/index.js',
   'prop-types/index.js',
   'scheduler/index.js',
+  'react-table',
 ];
 
 const cwd = process.cwd();
@@ -335,7 +337,11 @@ export async function install(
       rollupPluginCommonjs({
         extensions: ['.js', '.cjs'], // Default: [ '.js' ]
       }),
-      rollupPluginWrapInstallTargets(!!isTreeshake, CJS_PACKAGES_TO_AUTO_DETECT, installTargets),
+      rollupPluginWrapInstallTargets(
+        !!isTreeshake,
+        [...CJS_PACKAGES_TO_AUTO_DETECT, ...config.installOptions.namedExports],
+        installTargets,
+      ),
       rollupPluginDependencyStats((info) => (dependencyStats = info)),
       ...userDefinedRollup.plugins, // load user-defined plugins last
       rollupPluginCatchUnresolved(),

src/config.ts

@@ -108,6 +108,7 @@ export interface SnowpackConfig {
     sourceMap?: boolean | 'inline';
     externalPackage: string[];
     alias: {[key: string]: string};
+    namedExports: string[];
     rollup: {
       plugins: RollupPlugin[]; // for simplicity, only Rollup plugins are supported for now
       dedupe?: string[];
@@ -136,6 +137,7 @@ const DEFAULT_CONFIG: Partial<SnowpackConfig> = {
     installTypes: false,
     env: {},
     alias: {},
+    namedExports: [],
     rollup: {
       plugins: [],
       dedupe: [],
@@ -532,14 +534,14 @@ function validateConfigAgainstV1(rawConfig: any, cliFlags: any) {
   }
   if (rawConfig.namedExports) {
     handleDeprecatedConfigError(
-      '[Snowpack v1 -> v2] `namedExports` was removed in the latest version of Rollup, and should no longer be needed.',
+      '[Snowpack v1 -> v2] `rollup.namedExports` is no longer required. See also: installOptions.namedExports',
     );
   }
   if (rawConfig.installOptions?.rollup?.namedExports) {
     delete rawConfig.installOptions.rollup.namedExports;
     console.error(
       chalk.yellow(
-        '[Snowpack v2.3.0] `namedExports` was removed in the latest version of Rollup, and is now safe to remove from your config.',
+        '[Snowpack v2.3.0] `rollup.namedExports` is no longer required. See also: installOptions.namedExports',
       ),
     );
   }

src/rollup-plugin-wrap-install-targets.ts

@@ -33,7 +33,9 @@ export function rollupPluginWrapInstallTargets(
   const installTargetsByFile: {[loc: string]: InstallTarget[]} = {};
 
   function isAutoDetect(normalizedFileLoc: string) {
-    return autoDetectPackageExports.some((p) => normalizedFileLoc.includes(`node_modules/${p}`));
+    return autoDetectPackageExports.some((p) =>
+      normalizedFileLoc.includes(`node_modules/${p}${p.endsWith('index.js') ? '' : '/'}`),
+    );
   }
   return {
     name: 'snowpack:wrap-install-targets',

test/integration/config-named-exports/expected-install/import-map.json

@@ -0,0 +1,5 @@
+{
+  "imports": {
+    "mock-test-package": "./mock-test-package.js"
+  }
+}

test/integration/config-named-exports/expected-install/mock-test-package.js

@@ -0,0 +1,8 @@
+var entrypoint = {
+    export1: 'foo',
+    export2: 'bar',
+};
+var entrypoint_1 = entrypoint.export1;
+var entrypoint_2 = entrypoint.export2;
+
+export { entrypoint_1 as export1, entrypoint_2 as export2 };

test/integration/config-named-exports/expected-output.txt

@@ -0,0 +1,4 @@
+- snowpack installing...
+✔ snowpack install complete.
+  ⦿ web_modules/             size       gzip       brotli   
+    └─ mock-test-package.js    XXXX KB    XXXX KB    XXXX KB

test/integration/config-named-exports/package.json

@@ -0,0 +1,15 @@
+{
+  "description": "Handle installOptions.namedExports",
+  "scripts": {
+    "TEST": "node ../../../pkg/dist-node/index.bin.js"
+  },
+  "snowpack": {
+    "install": ["mock-test-package"],
+    "installOptions": {
+      "namedExports": ["mock-test-package"]
+    }
+  },
+  "dependencies": {
+    "mock-test-package": "^1.0.0"
+  }
+}