From ef952fa59a31580dd58b72158636908fdb8f9b9d Mon Sep 17 00:00:00 2001
From: Justin Fagnani <justin@fagnani.com>
Date: Mon, 29 Jan 2024 16:13:02 -0800
Subject: [PATCH] Speed up builds by not bundling typescript

---
 CHANGELOG.md                |  1 +
 rollup.config.typescript.js |  5 ++---
 rollup.config.web-worker.js | 11 ++++++++++-
 src/playground-project.ts   |  2 +-
 4 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index d2827297..7b488afc 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -18,6 +18,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 ### Changed
 
 - Upgraded to TypeScript 5.2 and Lit 3.0
+- **BREAKING** Use modules in workers. See [caniuse.com's support table](https://caniuse.com/mdn-api_worker_worker_ecmascript_modules) for browser support information.
 
 <!-- ### Added -->
 <!-- ### Fixed -->
diff --git a/rollup.config.typescript.js b/rollup.config.typescript.js
index 4ad01cbf..a440c401 100644
--- a/rollup.config.typescript.js
+++ b/rollup.config.typescript.js
@@ -23,9 +23,8 @@ import commonjs from '@rollup/plugin-commonjs';
  *   because we don't need to run the commonjs transform every time we build the
  *   worker.
  *
- * - We may want to use module imports in the worker at some point, for a faster
- *   development mode that doesn't bundle. Having only module sources will make
- *   this easier too.
+ * - We use module imports in the worker, for a faster development mode that
+ *   doesn't bundle. Having only module sources makes this easier too.
  */
 export default [
   {
diff --git a/rollup.config.web-worker.js b/rollup.config.web-worker.js
index 638649f2..9df03eca 100644
--- a/rollup.config.web-worker.js
+++ b/rollup.config.web-worker.js
@@ -6,12 +6,21 @@
 
 import resolve from '@rollup/plugin-node-resolve';
 import {maybeTerser} from './rollup.config.common.js';
+import * as path from 'path';
+
+const internalTypescriptPath = path.resolve(process.cwd(), 'internal/typescript.js');
 
 export default {
   input: 'typescript-worker/playground-typescript-worker.js',
+  external(id, parentId, isResolved) {
+    if (!isResolved && parentId !== undefined) {
+      id = path.resolve(path.dirname(parentId), id);
+    }
+    return id === internalTypescriptPath;
+  },
   output: {
     file: 'playground-typescript-worker.js',
-    format: 'iife',
+    format: 'esm',
     exports: 'none',
   },
   plugins: [resolve(), ...maybeTerser],
diff --git a/src/playground-project.ts b/src/playground-project.ts
index b5e40fad..2d485ec5 100644
--- a/src/playground-project.ts
+++ b/src/playground-project.ts
@@ -451,7 +451,7 @@ export class PlaygroundProject extends LitElement {
     let worker: Worker;
     if (typescriptWorkerScriptUrl.origin === window.location.origin) {
       // Easy case.
-      worker = new Worker(typescriptWorkerScriptUrl);
+      worker = new Worker(typescriptWorkerScriptUrl, {type: 'module'});
     } else {
       // If the worker script is different-origin, we need to fetch it ourselves
       // and create a blob URL.