Add first class Javascript/Typescript support to the Mill build tool (#…

…4003)

### Related Issues

#3927

### Checklist

- [x] **example/jslib/basic**
- [x] 1-simple/: A minimal Typescript module demonstrating
typechecking/running/testing/bundling of a Node CLI tool
- [x] 2-react/: A minimal Typescript module demonstrating
typechecking/running/testing/bundling of a React-based web application,
served using a static HTML page
- [x] 3-custom-build-logic/: A Typescript module with custom build logic

.gitignore

@@ -13,3 +13,7 @@ mill.iml
 bsp.log
 lowered.hnir
 .dotty-ide*
+node_modules/
+dist/
+build/
+*.bak

example/javascriptlib/basic/1-simple/build.mill

@@ -1,27 +1,34 @@
 package build
+
 import mill._, javascriptlib._
 
-object foo extends TypeScriptModule {
-  object bar extends TypeScriptModule {
-    def npmDeps = Seq("[email protected]")
-  }
-}
+object foo extends JestModule {
+  def npmDeps = Seq("[email protected]")
 
-object qux extends TypeScriptModule {
-  def moduleDeps = Seq(foo, foo.bar)
 }
 
-// Documentation for mill.javascriptlib
+// Documentation for mill.example.javascriptlib
 
 /** Usage
-
-> mill qux.run James Bond prof
+> mill foo.run James Bond prof
 Hello James Bond Professor
 
-> mill show qux.bundle
-".../out/qux/bundle.dest/bundle.js"
-
-> node out/qux/bundle.dest/bundle.js James Bond prof
+> mill foo.test
+PASS .../foo.test.ts
+...generateUser function
+...should generate a user with all specified fields...
+...should default lastName and role when they are not provided...
+...should default all fields when args is empty...
+...
+Test Suites:...1 passed, 1 total...
+Tests:...3 passed, 3 total...
+Snapshots:...
+Time:...
+Ran all test suites matching ...
+
+> mill show foo.bundle
+Build succeeded!
+
+> node out/foo/bundle.dest/bundle.js James Bond prof
 Hello James Bond Professor
-
 */

example/javascriptlib/basic/1-simple/foo/src/foo.ts

@@ -1,7 +1,33 @@
+import {Map} from 'node_modules/immutable';
+
 interface User {
     firstName: string
     lastName: string
     role: string
 }
 
-export {User}
+export const defaultRoles: Map<string, string> = Map({prof: "Professor"});
+
+/**
+ * Generate a user object based on command-line arguments
+ * @param args Command-line arguments
+ * @returns User object
+ */
+export function generateUser(args: string[]): User {
+    return {
+        firstName: args[0] || "unknown",
+        lastName: args[1] || "unknown",
+        role: defaultRoles.get(args[2], ""),
+    };
+}
+
+// Main CLI logic
+if (process.env.NODE_ENV !== "test") {
+    const args = process.argv.slice(2); // Skip 'node' and script name
+    const user = generateUser(args);
+
+    console.log(defaultRoles.toObject());
+    console.log(args[2]);
+    console.log(defaultRoles.get(args[2]));
+    console.log("Hello " + user.firstName + " " + user.lastName + " " + user.role);
+}

example/javascriptlib/basic/1-simple/foo/test/foo.test.ts

@@ -0,0 +1,64 @@
+import {generateUser, defaultRoles} from "../src/foo";
+import {Map} from 'node_modules/immutable';
+
+// Define the type roles object
+type RoleKeys = "admin" | "user";
+type Roles = {
+    [key in RoleKeys]: string;
+};
+
+// Mock `defaultRoles` as a global variable for testing
+const mockDefaultRoles = Map<string, string>({
+    admin: "Administrator",
+    user: "User",
+});
+
+describe("generateUser function", () => {
+    beforeAll(() => {
+        process.env.NODE_ENV = "test"; // Set NODE_ENV for all tests
+    });
+
+    afterEach(() => {
+        jest.clearAllMocks();
+    });
+
+    test("should generate a user with all specified fields", () => {
+        // Override the `defaultRoles` map for testing
+        (defaultRoles as any).get = mockDefaultRoles.get.bind(mockDefaultRoles);
+
+        const args = ["John", "Doe", "admin"];
+        const user = generateUser(args);
+
+        expect(user).toEqual({
+            firstName: "John",
+            lastName: "Doe",
+            role: "Administrator",
+        });
+    });
+
+    test("should default lastName and role when they are not provided", () => {
+        (defaultRoles as any).get = mockDefaultRoles.get.bind(mockDefaultRoles);
+
+        const args = ["Jane"];
+        const user = generateUser(args);
+
+        expect(user).toEqual({
+            firstName: "Jane",
+            lastName: "unknown",
+            role: "",
+        });
+    });
+
+    test("should default all fields when args is empty", () => {
+        (defaultRoles as any).get = mockDefaultRoles.get.bind(mockDefaultRoles);
+
+        const args: string[] = [];
+        const user = generateUser(args);
+
+        expect(user).toEqual({
+            firstName: "unknown",
+            lastName: "unknown",
+            role: "",
+        });
+    });
+});

example/javascriptlib/basic/1-simple/jest.config.ts

@@ -0,0 +1,13 @@
+export default {
+    preset: 'ts-jest',
+    testEnvironment: 'node',
+    testMatch: [
+        '<rootDir>/**/test/**/*.test.ts',
+        '<rootDir>/**/test/**/*.test.js',
+    ],
+    transform: {
+        '^.+\\.(ts|tsx)$': ['ts-jest', { tsconfig: 'tsconfig.json' }],
+        '^.+\\.(js|jsx)$': 'babel-jest', // Use babel-jest for JS/JSX files
+    },
+    moduleFileExtensions: ['ts', 'tsx', 'js', 'jsx', 'json', 'node']
+};

example/javascriptlib/basic/2-react/build.mill

@@ -0,0 +1,26 @@
+package build
+
+import mill._, javascriptlib._
+
+object foo extends RsWithServeModule {
+  override def mkENV = Task {
+    super.mkENV() ++ Map("PORT" -> "3000")
+  }
+}
+
+// Documentation for mill.example.javascriptlib
+
+/** Usage
+
+> mill foo.test
+PASS src/test/App.test.tsx
+...renders learn react link...
+Test Suites:...1 passed, 1 total
+Tests:...1 passed, 1 total
+Snapshots:...
+Time:...
+Ran all test suites...
+
+> mill show foo.bundle # build the react app with react-scripts # `foo.run` serves static html using serve
+...
+*/

example/javascriptlib/basic/2-react/foo/public/index.html

@@ -0,0 +1,43 @@
+<!DOCTYPE html>
+<html lang="en">
+  <head>
+    <meta charset="utf-8" />
+    <link rel="icon" href="%PUBLIC_URL%/favicon.ico" />
+    <meta name="viewport" content="width=device-width, initial-scale=1" />
+    <meta name="theme-color" content="#000000" />
+    <meta
+      name="description"
+      content="Web site created using create-react-app"
+    />
+    <link rel="apple-touch-icon" href="%PUBLIC_URL%/logo192.png" />
+    <!--
+      manifest.json provides metadata used when your web app is installed on a
+      user's mobile device or desktop. See https://developers.google.com/web/fundamentals/web-app-manifest/
+    -->
+    <link rel="manifest" href="%PUBLIC_URL%/manifest.json" />
+    <!--
+      Notice the use of %PUBLIC_URL% in the tags above.
+      It will be replaced with the URL of the `public` folder during the build.
+      Only files inside the `public` folder can be referenced from the HTML.
+
+      Unlike "/favicon.ico" or "favicon.ico", "%PUBLIC_URL%/favicon.ico" will
+      work correctly both with client-side routing and a non-root public URL.
+      Learn how to configure a non-root public URL by running `npm run build`.
+    -->
+    <title>React App</title>
+  </head>
+  <body>
+    <noscript>You need to enable JavaScript to run this app.</noscript>
+    <div id="root"></div>
+    <!--
+      This HTML file is a template.
+      If you open it directly in the browser, you will see an empty page.
+
+      You can add webfonts, meta tags, or analytics to this file.
+      The build step will place the bundled scripts into the <body> tag.
+
+      To begin the development, run `npm start` or `yarn start`.
+      To create a production bundle, use `npm run build` or `yarn build`.
+    -->
+  </body>
+</html>

example/javascriptlib/basic/2-react/foo/public/manifest.json

@@ -0,0 +1,25 @@
+{
+  "short_name": "React App",
+  "name": "Create React App Sample",
+  "icons": [
+    {
+      "src": "favicon.ico",
+      "sizes": "64x64 32x32 24x24 16x16",
+      "type": "image/x-icon"
+    },
+    {
+      "src": "logo192.png",
+      "type": "image/png",
+      "sizes": "192x192"
+    },
+    {
+      "src": "logo512.png",
+      "type": "image/png",
+      "sizes": "512x512"
+    }
+  ],
+  "start_url": ".",
+  "display": "standalone",
+  "theme_color": "#000000",
+  "background_color": "#ffffff"
+}

example/javascriptlib/basic/2-react/foo/public/robots.txt

@@ -0,0 +1,3 @@
+# https://www.robotstxt.org/robotstxt.html
+User-agent: *
+Disallow:

example/javascriptlib/basic/2-react/foo/src/App.css

@@ -0,0 +1,38 @@
+.App {
+  text-align: center;
+}
+
+.App-logo {
+  height: 40vmin;
+  pointer-events: none;
+}
+
+@media (prefers-reduced-motion: no-preference) {
+  .App-logo {
+    animation: App-logo-spin infinite 20s linear;
+  }
+}
+
+.App-header {
+  background-color: #282c34;
+  min-height: 100vh;
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  justify-content: center;
+  font-size: calc(10px + 2vmin);
+  color: white;
+}
+
+.App-link {
+  color: #61dafb;
+}
+
+@keyframes App-logo-spin {
+  from {
+    transform: rotate(0deg);
+  }
+  to {
+    transform: rotate(360deg);
+  }
+}

example/javascriptlib/basic/2-react/foo/src/app/App.tsx

@@ -0,0 +1,26 @@
+import React from 'react';
+import logo from 'src/logo.svg';
+import 'src/App.css';
+
+function App() {
+  return (
+    <div className="App">
+      <header className="App-header">
+        <img src={logo} className="App-logo" alt="logo" />
+        <p>
+          Edit <code>src/App.tsx</code> and save to reload.
+        </p>
+        <a
+          className="App-link"
+          href="https://reactjs.org"
+          target="_blank"
+          rel="noopener noreferrer"
+        >
+          Learn React
+        </a>
+      </header>
+    </div>
+  );
+}
+
+export default App;

example/javascriptlib/basic/2-react/foo/src/index.css

@@ -0,0 +1,13 @@
+body {
+  margin: 0;
+  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen',
+    'Ubuntu', 'Cantarell', 'Fira Sans', 'Droid Sans', 'Helvetica Neue',
+    sans-serif;
+  -webkit-font-smoothing: antialiased;
+  -moz-osx-font-smoothing: grayscale;
+}
+
+code {
+  font-family: source-code-pro, Menlo, Monaco, Consolas, 'Courier New',
+    monospace;
+}

example/javascriptlib/basic/2-react/foo/src/index.tsx

@@ -0,0 +1,19 @@
+import React from 'react';
+import ReactDOM from 'react-dom/client';
+import './index.css';
+import App from './app/App';
+import reportWebVitals from './reportWebVitals';
+
+const root = ReactDOM.createRoot(
+  document.getElementById('root') as HTMLElement
+);
+root.render(
+  <React.StrictMode>
+    <App />
+  </React.StrictMode>
+);
+
+// If you want to start measuring performance in your app, pass a function
+// to log results (for example: reportWebVitals(console.log))
+// or send to an analytics endpoint. Learn more: https://bit.ly/CRA-vitals
+reportWebVitals();