fix(es): Handle import assertions correctly (#3113)

swc_ecma_codegen:
 - Implement codegen for static import assertions.

swc_ecma_transforms_proposal:
  - `import_assertions`: Support `export`s.

swc:
 - Add `jsc.experimental.keep_import_assertions`.

node-swc:
 - Fix typo.

crates/swc/src/config/mod.rs

@@ -365,7 +365,9 @@ impl Options {
                 }),
                 syntax.decorators()
             ),
-            import_assertions(),
+            // The transform strips import assertions, so it's only enabled if
+            // keep_import_assertions is false.
+            Optional::new(import_assertions(), !experimental.keep_import_assertions),
             // Do a resolver pass after decorators as it might
             // emit runtime declarations and do it before
             // type stripping as we need to know scope information
@@ -932,6 +934,9 @@ pub struct JscExperimental {
     /// This requires cargo feature `plugin`.
     #[serde(default)]
     pub plugins: Option<Vec<PluginConfig>>,
+    /// If true, keeps import assertions in the output.
+    #[serde(default)]
+    pub keep_import_assertions: bool,
 }
 
 impl Merge for JscExperimental {

crates/swc_ecma_codegen/src/lib.rs

@@ -275,6 +275,14 @@ where
         }
 
         emit!(n.src);
+
+        if let Some(asserts) = &n.asserts {
+            formatting_space!();
+            keyword!("assert");
+            formatting_space!();
+            emit!(asserts);
+        }
+
         formatting_semi!();
     }
 
@@ -402,6 +410,13 @@ where
             keyword!("from");
             formatting_space!();
             emit!(src);
+
+            if let Some(asserts) = &node.asserts {
+                formatting_space!();
+                keyword!("assert");
+                formatting_space!();
+                emit!(asserts);
+            }
         }
         formatting_semi!();
     }
@@ -417,6 +432,14 @@ where
         keyword!("from");
         formatting_space!();
         emit!(node.src);
+
+        if let Some(asserts) = &node.asserts {
+            formatting_space!();
+            keyword!("assert");
+            formatting_space!();
+            emit!(asserts);
+        }
+
         formatting_semi!();
     }
 

crates/swc_ecma_codegen/tests/fixture/issues/3110/input.js

@@ -0,0 +1,5 @@
+import data from "./data.json" assert { type: "json" };
+export { default as data2 } from "./data2.json" assert { type: "json" };
+export * as data3 from "./data3.json" assert { type: "json" };
+
+console.log(data);

crates/swc_ecma_codegen/tests/fixture/issues/3110/output.js

@@ -0,0 +1,10 @@
+import data from "./data.json" assert {
+    type: "json"
+};
+export { default as data2 } from "./data2.json" assert {
+    type: "json"
+};
+export * as data3 from "./data3.json" assert {
+    type: "json"
+};
+console.log(data);

crates/swc_ecma_codegen/tests/fixture/issues/3110/output.min.js

@@ -0,0 +1 @@
+import data from"./data.json"assert{type:"json"};export{default as data2}from"./data2.json"assert{type:"json"};export*as data3 from"./data3.json"assert{type:"json"};console.log(data)

crates/swc_ecma_transforms_proposal/src/import_assertions.rs

@@ -1,4 +1,4 @@
-use swc_ecma_ast::ImportDecl;
+use swc_ecma_ast::{ExportAll, ImportDecl, NamedExport};
 use swc_ecma_visit::{as_folder, noop_visit_mut_type, Fold, VisitMut};
 
 pub fn import_assertions() -> impl VisitMut + Fold {
@@ -12,4 +12,12 @@ impl VisitMut for ImportAssertions {
     fn visit_mut_import_decl(&mut self, n: &mut ImportDecl) {
         n.asserts = None;
     }
+
+    fn visit_mut_export_all(&mut self, n: &mut ExportAll) {
+        n.asserts = None;
+    }
+
+    fn visit_mut_named_export(&mut self, n: &mut NamedExport) {
+        n.asserts = None;
+    }
 }

crates/swc_ecma_transforms_proposal/tests/import_assertions.rs

@@ -0,0 +1,39 @@
+use swc_ecma_parser::{EsConfig, Syntax};
+use swc_ecma_transforms_proposal::import_assertions;
+use swc_ecma_transforms_testing::test;
+use swc_ecma_visit::Fold;
+
+fn tr() -> impl Fold {
+    import_assertions()
+}
+
+fn syntax() -> Syntax {
+    Syntax::Es(EsConfig {
+        import_assertions: true,
+        ..Default::default()
+    })
+}
+
+test!(
+    syntax(),
+    |_| tr(),
+    import_with_assertions,
+    r#"import test from "./test.json" assert {type: "json"};"#,
+    r#"import test from "./test.json";"#
+);
+
+test!(
+    syntax(),
+    |_| tr(),
+    named_export_with_assertions,
+    r#"export {default as test} from "./test.json" assert {type: "json"};"#,
+    r#"export {default as test} from "./test.json";"#
+);
+
+test!(
+    syntax(),
+    |_| tr(),
+    export_all_with_assertions,
+    r#"export * from "./test.json" assert {type: "json"};"#,
+    r#"export * from "./test.json";"#
+);

crates/swc_ecma_transforms_typescript/tests/strip_correctness.rs

@@ -156,6 +156,7 @@ fn identity(entry: PathBuf) {
                 decorators_before_export: true,
                 export_default_from: true,
                 private_in_object: true,
+                import_assertions: true,
                 ..Default::default()
             }),
             (&*js_fm).into(),

node-swc/src/types.ts

@@ -490,8 +490,9 @@ export interface JscConfig {
    */
   keepClassNames?: boolean
 
-  experimetal?: {
-    optimizeHygiene?: boolean
+  experimental?: {
+    optimizeHygiene?: boolean,
+    keepImportAssertions?: boolean
   },
 
   baseUrl?: string