Strip TypeScript class properties without value assigned (#956)

Co-authored-by: 강동윤 <kdy1997.dev@gmail.com>

ecmascript/transforms/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "swc_ecma_transforms"
-version = "0.19.3"
+version = "0.19.4"
 authors = ["강동윤 <kdy1997.dev@gmail.com>"]
 license = "Apache-2.0/MIT"
 repository = "https://github.com/swc-project/swc.git"

ecmascript/transforms/src/compat/es2020/class_properties.rs

@@ -388,6 +388,8 @@ impl ClassProperties {
                         }
                     };
 
+                    let assigned_value = prop.value.is_some();
+
                     let value = prop.value.unwrap_or_else(|| undefined(prop_span));
                     let value = if prop.is_static {
                         value
@@ -427,7 +429,7 @@ impl ClassProperties {
                                 }
                                 .into_stmt(),
                             );
-                        } else {
+                        } else if assigned_value {
                             constructor_exprs.push(Box::new(Expr::Assign(AssignExpr {
                                 span: DUMMY_SP,
                                 left: (PatOrExpr::Expr(Box::new(

ecmascript/transforms/tests/typescript_strip.rs

@@ -762,6 +762,9 @@ test!(
     "class A extends B {
             foo = 'foo'
             b = this.a;
+
+            declare1
+            declare2!: string
           
             constructor(private readonly a: string, readonly c, private d: number = 1) {
                 super()

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@swc/core",
-  "version": "1.2.17",
+  "version": "1.2.18",
   "description": "Super-fast alternative for babel",
   "main": "./index.js",
   "author": "강동윤 <kdy1997.dev@gmail.com>",