build: support preact 🥳 (#7255)

* build: support preact

* add log

* Simplify the config and generate prod and dev builds for preact

* update changelog

* remove logs

* use env variable so its available during build time

* update cl

* fix

src/packages/excalidraw/CHANGELOG.md

@@ -37,6 +37,18 @@ Please add the latest change on the top under the correct section.
 
 - [`useDevice`](https://docs.excalidraw.com/docs/@excalidraw/excalidraw/api/utils#usedevice) hook's return value was changed to differentiate between `editor` and `viewport` breakpoints. [#7243](https://github.com/excalidraw/excalidraw/pull/7243)
 
+### Build
+
+- Support Preact [#7255](https://github.com/excalidraw/excalidraw/pull/7255). The host needs to set `process.env.IS_PREACT` to `true`
+
+When using vite, you will have to make sure the variable process.env.IS_PREACT is available at runtime since Vite removes it by default, so you can update the vite config to ensure its available
+
+```json
+define: {
+  "process.env.IS_PREACT": process.env.IS_PREACT,
+}
+```
+
 ## 0.16.1 (2023-09-21)
 
 ## Excalidraw Library

src/packages/excalidraw/main.js

@@ -1,4 +1,10 @@
-if (process.env.NODE_ENV === "production") {
+if (process.env.IS_PREACT === "true") {
+  if (process.env.NODE_ENV === "production") {
+    module.exports = require("./dist/excalidraw-with-preact.production.min.js");
+  } else {
+    module.exports = require("./dist/excalidraw-with-preact.development.js");
+  }
+} else if (process.env.NODE_ENV === "production") {
   module.exports = require("./dist/excalidraw.production.min.js");
 } else {
   module.exports = require("./dist/excalidraw.development.js");

src/packages/excalidraw/package.json

@@ -78,7 +78,7 @@
   "homepage": "https://github.com/excalidraw/excalidraw/tree/master/src/packages/excalidraw",
   "scripts": {
     "gen:types": "tsc --project ../../../tsconfig-types.json",
-    "build:umd": "rm -rf dist && cross-env NODE_ENV=production webpack --config webpack.prod.config.js && cross-env NODE_ENV=development webpack --config webpack.dev.config.js && yarn gen:types",
+    "build:umd": "rm -rf dist && cross-env NODE_ENV=production webpack --config webpack.prod.config.js && cross-env NODE_ENV=development webpack --config webpack.dev.config.js && NODE_ENV=development webpack --config webpack.preact.config.js && NODE_ENV=production webpack --config webpack.preact.config.js && yarn gen:types",
     "build:umd:withAnalyzer": "cross-env NODE_ENV=production ANALYZER=true webpack --config webpack.prod.config.js",
     "pack": "yarn build:umd && yarn pack",
     "start": "webpack serve --config webpack.dev-server.config.js",

src/packages/excalidraw/webpack.preact.config.js

@@ -0,0 +1,33 @@
+const { merge } = require("webpack-merge");
+
+const prodConfig = require("./webpack.prod.config");
+const devConfig = require("./webpack.dev.config");
+
+const isProd = process.env.NODE_ENV === "production";
+
+const config = isProd ? prodConfig : devConfig;
+const outputFile = isProd
+  ? "excalidraw-with-preact.production.min"
+  : "excalidraw-with-preact.development";
+
+const preactWebpackConfig = {
+  entry: {
+    [outputFile]: "./entry.js",
+  },
+  externals: {
+    ...config.externals,
+    "react-dom/client": {
+      root: "ReactDOMClient",
+      commonjs2: "react-dom/client",
+      commonjs: "react-dom/client",
+      amd: "react-dom/client",
+    },
+    "react/jsx-runtime": {
+      root: "ReactJSXRuntime",
+      commonjs2: "react/jsx-runtime",
+      commonjs: "react/jsx-runtime",
+      amd: "react/jsx-runtime",
+    },
+  },
+};
+module.exports = merge(config, preactWebpackConfig);