fix: respect useDefineForClassFields=false setting (#156)

Co-authored-by: hanlee <[email protected]>

Author: orgads

src/index.ts

@@ -84,6 +84,10 @@ export default createUnplugin<Options | undefined, false>(
           jsc.target = compilerOptions.target
         }
 
+        if (compilerOptions.useDefineForClassFields != null) {
+          jsc.transform.useDefineForClassFields = compilerOptions.useDefineForClassFields
+        }
+
         if (options.jsc) {
           jsc = defu<SWCOptions, SWCOptions[]>(options.jsc, jsc)
         }

test/fixtures/class-fields/class-field.ts

@@ -0,0 +1,3 @@
+export class TestClass {
+  inlineProperty = 'value';
+}

test/fixtures/class-fields/tsconfig.json

@@ -0,0 +1,8 @@
+{
+  "compilerOptions": {
+    "target": "es2020",
+    "module": "esnext",
+    "strict": true,
+    "useDefineForClassFields": false
+  }
+}

test/index.test.ts

@@ -93,3 +93,21 @@ it('minify', async () => {
     "
   `)
 })
+
+it('useDefineForClassFields=false', async () => {
+  const bundle = await rollup({
+    input: fixture('class-fields/class-field.ts'),
+    plugins: [
+      swc.rollup(),
+    ],
+  })
+
+  const { output } = await bundle.generate({
+    format: 'esm',
+    dir: fixture('class-fields/dist'),
+  })
+
+  const code = output[0].code
+  // Ensure inline property is moved to constructor
+  expect(code).toContain('this.inlineProperty = \'value\'')
+})