Lit workers

.eslintignore

@@ -329,6 +329,11 @@ packages/labs/vue-utils/node_modules/
 packages/labs/vue-utils/index.*
 packages/labs/vue-utils/wrapper-utils.*
 
+packages/labs/workers/development/
+packages/labs/workers/test/
+packages/labs/workers/lib/
+packages/labs/workers/index.*
+
 packages/labs/test-projects/test-element-a/**/*.d.ts
 packages/labs/test-projects/test-element-a/**/*.d.ts.map
 packages/labs/test-projects/test-element-a/**/*.js

.prettierignore

@@ -313,6 +313,11 @@ packages/labs/vue-utils/node_modules/
 packages/labs/vue-utils/index.*
 packages/labs/vue-utils/wrapper-utils.*
 
+packages/labs/workers/development/
+packages/labs/workers/test/
+packages/labs/workers/lib/
+packages/labs/workers/index.*
+
 packages/lit-starter-js/node_modules/*
 packages/lit-starter-js/docs/*
 packages/lit-starter-js/docs-src/*

packages/labs/ssr/src/lib/dom-shim.ts

@@ -12,7 +12,6 @@
  * CustomElementRegistry however.
  */
 
-import fetch from 'node-fetch';
 import {
   HTMLElement,
   Element,
@@ -52,6 +51,7 @@ export const getWindow = ({
 
   class CSSStyleSheet {
     replace() {}
+    replaceSync() {}
   }
 
   const window = {
@@ -80,7 +80,7 @@ export const getWindow = ({
     requestAnimationFrame() {},
 
     // Set below
-    window: undefined as unknown,
+    window: globalThis,
 
     // User-provided globals, like `require`
     ...props,
@@ -123,11 +123,22 @@ export const getWindow = ({
   return window;
 };
 
-export const installWindowOnGlobal = (props: {[key: string]: unknown} = {}) => {
+export const installWindowOnGlobal = (
+  props: {[key: string]: unknown} = {},
+  installWindow = false
+) => {
   // Avoid installing the DOM shim if one already exists
   if (globalThis.window === undefined) {
     const window = getWindow({props});
     // Copy initial window globals to node global
-    Object.assign(globalThis, window);
+    // Object.assign(globalThis, window);
+    for (const [key, value] of Object.entries(window)) {
+      Object.defineProperty(globalThis, key, {value, writable: true});
+    }
+    if (installWindow) {
+      // Object.defineProperty(globalThis, 'window', {value: globalThis});
+      // eslint-disable-next-line
+      // (globalThis as any).window = globalThis;
+    }
   }
 };

packages/labs/workers/.gitignore

@@ -0,0 +1,4 @@
+/development/
+/test/
+/lib/
+/index.*

packages/labs/workers/CHANGELOG.md

@@ -0,0 +1 @@
+# Change Log

packages/labs/workers/LICENSE

@@ -0,0 +1,28 @@
+BSD 3-Clause License
+
+Copyright (c) 2023 Google LLC. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. Redistributions in binary form must reproduce the above copyright notice,
+   this list of conditions and the following disclaimer in the documentation
+   and/or other materials provided with the distribution.
+
+3. Neither the name of the copyright holder nor the names of its
+   contributors may be used to endorse or promote products derived from
+   this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

packages/labs/workers/README.md

@@ -0,0 +1,18 @@
+# @lit-labs/workers
+
+This package will allow Lit templates and components to be run inside a worker and render to the main document. It is highly experimental.
+
+## Example
+
+```ts
+import {createWorkerElement} from '../lib/worker-element.js';
+
+const localElementClass = createWorkerElement({
+  tagName: 'test-element',
+  url: new URL('./test-element.js', import.meta.url).href,
+  attributes: ['name'],
+});
+customElements.define('local-test-element', localElementClass);
+```
+
+Then every instance of `<local-test-element>` will get and run in its own worker.

packages/labs/workers/package.json

@@ -0,0 +1,149 @@
+{
+  "name": "@lit-labs/workers",
+  "version": "0.0.0",
+  "private": true,
+  "description": "Allows Lit to be run in web workers",
+  "license": "BSD-3-Clause",
+  "homepage": "https://lit.dev/",
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/lit/lit.git",
+    "directory": "packages/labs/workers"
+  },
+  "type": "module",
+  "main": "index.js",
+  "module": "index.js",
+  "typings": "index.d.ts",
+  "directories": {
+    "test": "test"
+  },
+  "exports": {
+    ".": {
+      "development": "./development/index.js",
+      "default": "./index.js"
+    }
+  },
+  "files": [
+    "/development/",
+    "!/development/test/",
+    "/index.{d.ts,d.ts.map,js,js.map}"
+  ],
+  "scripts": {
+    "build": "wireit",
+    "build:ts": "wireit",
+    "build:ts:types": "wireit",
+    "build:rollup": "wireit",
+    "test": "wireit",
+    "test:dev": "wireit",
+    "test:prod": "wireit",
+    "checksize": "wireit"
+  },
+  "wireit": {
+    "build": {
+      "dependencies": [
+        "build:ts",
+        "build:ts:types",
+        "build:rollup",
+        "../../lit:build"
+      ]
+    },
+    "build:ts": {
+      "command": "tsc --build --pretty",
+      "clean": "if-file-deleted",
+      "dependencies": [
+        "../../lit:build:ts:types",
+        "../ssr:build:ts"
+      ],
+      "files": [
+        "src/**/*.ts",
+        "tsconfig.json"
+      ],
+      "output": [
+        "development",
+        "tsconfig.tsbuildinfo"
+      ]
+    },
+    "build:ts:types": {
+      "command": "treemirror development . \"**/*.d.ts{,.map}\"",
+      "dependencies": [
+        "../../internal-scripts:build",
+        "build:ts"
+      ],
+      "files": [],
+      "output": [
+        "*.d.ts{,.map}"
+      ]
+    },
+    "build:rollup": {
+      "command": "rollup -c",
+      "dependencies": [
+        "build:ts"
+      ],
+      "files": [
+        "rollup.config.js",
+        "../../../rollup-common.js"
+      ],
+      "output": [
+        "index.js{,.map}"
+      ]
+    },
+    "test": {
+      "dependencies": [
+        "test:dev",
+        "test:prod"
+      ]
+    },
+    "test:dev": {
+      "command": "MODE=dev node ../../tests/run-web-tests.js \"development/test/**/*_test.js\" --config ../../tests/web-test-runner.config.js",
+      "dependencies": [
+        "build",
+        "../../tests:build"
+      ],
+      "env": {
+        "BROWSERS": {
+          "external": true
+        }
+      },
+      "files": [],
+      "output": []
+    },
+    "test:prod": {
+      "command": "MODE=prod node ../../tests/run-web-tests.js \"development/test/**/*_test.js\" --config ../../tests/web-test-runner.config.js",
+      "dependencies": [
+        "build",
+        "../../tests:build"
+      ],
+      "env": {
+        "BROWSERS": {
+          "external": true
+        }
+      },
+      "files": [],
+      "output": []
+    },
+    "checksize": {
+      "command": "rollup -c --environment=CHECKSIZE",
+      "dependencies": [
+        "build:ts"
+      ],
+      "files": [
+        "rollup.config.js",
+        "../../../rollup-common.js"
+      ],
+      "output": []
+    }
+  },
+  "author": "Google LLC",
+  "devDependencies": {
+    "@lit-internal/scripts": "^1.0.0"
+  },
+  "dependencies": {
+    "lit": "^2.0.0",
+    "lit-html": "^2.0.0",
+    "@lit/reactive-element": "^1.0.0",
+    "@lit-labs/ssr": "^3.0.0"
+  },
+  "publishConfig": {
+    "access": "public"
+  }
+}

packages/labs/workers/rollup.config.js

@@ -0,0 +1,14 @@
+/**
+ * @license
+ * Copyright 2018 Google LLC
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+import {litProdConfig} from '../../../rollup-common.js';
+import {createRequire} from 'module';
+
+export default litProdConfig({
+  packageName: createRequire(import.meta.url)('./package.json').name,
+  entryPoints: ['index'],
+  external: [],
+});

packages/labs/workers/src/index.ts

@@ -0,0 +1,7 @@
+/**
+ * @license
+ * Copyright 2023 Google LLC
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+export {};

packages/labs/workers/src/lib/install-dom-shim.ts

@@ -0,0 +1,2 @@
+import {installWindowOnGlobal} from '@lit-labs/ssr/lib/dom-shim.js';
+installWindowOnGlobal({}, true);

packages/labs/workers/src/lib/types.ts

@@ -0,0 +1,59 @@
+/**
+ * @license
+ * Copyright 2023 Google LLC
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+import type {PropertyDeclaration, PropertyValues, TemplateResult} from 'lit';
+
+/**
+ * @fileoverview
+ *
+ * Common interfaces for cross-thread messages.
+ */
+
+export type Message =
+  | InitializeMessage
+  | InitializeReplyMessage
+  | RenderMessage
+  | RenderReplyMessage
+  | ErrorMessage;
+
+export type MessageKind = Message['kind'];
+
+export interface InitializeMessage {
+  kind: 'initialize';
+  url: string;
+  tagName: string;
+}
+
+export interface InitializeReplyMessage {
+  kind: 'initialize-reply';
+  styles: Array<StyleMessage>;
+  properties: {[key: string]: PropertyDeclaration};
+}
+
+export interface RenderMessage {
+  kind: 'render';
+  changedProperties: PropertyValues;
+  currentValues: Record<string, unknown>;
+  currentAttributes: Record<string, string>;
+}
+
+export interface RenderReplyMessage {
+  kind: 'render-reply';
+  result: TemplateResult;
+}
+
+export interface ErrorMessage {
+  kind: 'error';
+  errors: Array<string>;
+}
+
+/**
+ * Represents a CSSResult
+ */
+export interface StyleMessage {
+  id: number;
+  cssText?: string;
+}