feat(json): add includeArbitraryNames option (rollup#1641)

.eslintignore

@@ -7,3 +7,7 @@ packages/typescript/test/fixtures/syntax-error
 
 # temporary workaround for eslint bug where package.json is a directory
 packages/node-resolve/test/fixtures/package-json-in-path
+
+# temporary workaround for TypeScript as it doesn't support "Arbitrary module namespace identifier names"
+# https://github.com/microsoft/TypeScript/issues/40594
+packages/json/test/fixtures/arbitrary/main.js

packages/json/README.md

@@ -75,6 +75,13 @@ Default: `null`
 
 A [picomatch pattern](https://github.com/micromatch/picomatch), or array of patterns, which specifies the files in the build the plugin should operate on. By default all files are targeted.
 
+### `includeArbitraryNames`
+
+Type: `Boolean`<br>
+Default: `false`
+
+If `true` and `namedExports` is `true`, generates a named export for not a valid identifier properties of the JSON object by leveraging the ["Arbitrary Module Namespace Identifier Names" feature](https://github.com/tc39/ecma262/pull/2154).
+
 ### `indent`
 
 Type: `String`<br>

packages/json/package.json

@@ -61,7 +61,7 @@
     }
   },
   "dependencies": {
-    "@rollup/pluginutils": "^5.0.1"
+    "@rollup/pluginutils": "^5.1.0"
   },
   "devDependencies": {
     "@rollup/plugin-buble": "^1.0.0",

packages/json/src/index.js

@@ -18,6 +18,7 @@ export default function json(options = {}) {
             preferConst: options.preferConst,
             compact: options.compact,
             namedExports: options.namedExports,
+            includeArbitraryNames: options.includeArbitraryNames,
             indent
           }),
           map: { mappings: '' }

packages/json/test/fixtures/arbitrary/foo.json

@@ -0,0 +1,3 @@
+{
+  "foo.bar": "baz"
+}

packages/json/test/fixtures/arbitrary/main.js

@@ -0,0 +1,3 @@
+export { 'foo.bar' as bar } from './foo.json';
+
+result = exports; // eslint-disable-line no-undef

packages/json/test/test.js

@@ -54,6 +54,17 @@ test('generates named exports', async (t) => {
   t.is(code.indexOf('this-should-be-excluded'), -1, 'should exclude unused properties');
 });
 
+test('generates named exports including arbitrary names', async (t) => {
+  const bundle = await rollup({
+    input: 'fixtures/arbitrary/main.js',
+    plugins: [json({ includeArbitraryNames: true })]
+  });
+
+  const { result } = await testBundle(t, bundle, { inject: { exports: {} } });
+
+  t.is(result.bar, 'baz');
+});
+
 test('resolves extensionless imports in conjunction with the node-resolve plugin', async (t) => {
   const bundle = await rollup({
     input: 'fixtures/extensionless/main.js',