fix: support new syntax in webpack@4 (#219)

webpack/webpack#10227

Author: buschtoens

src/index.js

@@ -50,7 +50,14 @@ module.exports = {
             [
               require.resolve('@babel/plugin-proposal-class-properties'),
               { loose: true }
-            ]
+            ],
+
+            // https://github.com/webpack/webpack/issues/10227
+            // Remove when `ember-auto-import` updates to `webpack@5`.
+            require.resolve(
+              '@babel/plugin-proposal-nullish-coalescing-operator'
+            ),
+            require.resolve('@babel/plugin-proposal-optional-chaining')
           ],
           presets: [
             // Transpile incompatible syntax for project build targets

src/package.json

@@ -18,6 +18,8 @@
   "dependencies": {
     "@babel/plugin-proposal-class-properties": "^7.12.1",
     "@babel/plugin-proposal-decorators": "^7.12.1",
+    "@babel/plugin-proposal-nullish-coalescing-operator": "^7.12.1",
+    "@babel/plugin-proposal-optional-chaining": "^7.12.1",
     "@babel/plugin-transform-typescript": "^7.12.1",
     "@babel/preset-env": "^7.12.1"
   },

tests/app/tests/unit/ts-module-a-test.js

@@ -1,12 +1,13 @@
 import { module, test } from 'qunit';
 
-import { works, SomeEnum, moduleB } from '@test/ts-module-a';
+import { works, SomeEnum, moduleB, foo } from '@test/ts-module-a';
 
 module('ts-module-a', function () {
   test('it works', function (assert) {
     assert.ok(works());
     assert.ok('Foo' in SomeEnum);
     assert.ok('Bar' in SomeEnum);
     assert.ok(moduleB.nestedWorks());
+    assert.ok(foo === 'foo');
   });
 });

tests/ts-module-a/index.ts

@@ -15,4 +15,12 @@ export class SomeClass {
   declare someDeclaredProperty: true;
 }
 
+declare global {
+  interface Window {
+    foo?: { bar?: string };
+  }
+}
+
+export const foo = window.foo?.bar ?? 'foo';
+
 export type { SomeType } from './types-only';