Add import-esm flag (#192)

Add "import-esm" feature to make `import`s have a `.js` extension

ts-rs/Cargo.toml

@@ -30,6 +30,7 @@ indexmap-impl = ["indexmap"]
 ordered-float-impl = ["ordered-float"]
 heapless-impl = ["heapless"]
 no-serde-warnings = ["ts-rs-macros/no-serde-warnings"]
+import-esm = []
 
 [dev-dependencies]
 serde = { version = "1.0", features = ["derive"] }

ts-rs/src/export.rs

@@ -110,12 +110,18 @@ fn generate_imports<T: TS + ?Sized + 'static>(out: &mut String) -> Result<(), Ex
 fn import_path(from: &Path, import: &Path) -> String {
     let rel_path =
         diff_paths(import, from.parent().unwrap()).expect("failed to calculate import path");
-    match rel_path.components().next() {
+    let path = match rel_path.components().next() {
         Some(Component::Normal(_)) => format!("./{}", rel_path.to_string_lossy()),
         _ => rel_path.to_string_lossy().into(),
+    };
+
+    let path_without_extension = path.trim_end_matches(".ts");
+
+    if cfg!(feature = "import-esm") {
+        format!("{}.js", path_without_extension)
+    } else {
+        path_without_extension.to_owned()
     }
-    .trim_end_matches(".ts")
-    .to_owned()
 }
 
 // Construct a relative path from a provided base directory path to the provided path.

ts-rs/src/lib.rs

@@ -64,6 +64,7 @@
 //! - generate necessary imports when exporting to multiple files
 //! - serde compatibility
 //! - generic types
+//! - support for ESM imports
 //!
 //! ## limitations
 //! - generic fields cannot be inlined or flattened (#56)
@@ -112,6 +113,10 @@
 //!   When `serde-compat` is enabled, warnings are printed during build if unsupported serde
 //!   attributes are encountered. Enabling this feature silences these warnings.
 //!
+//! - `import-esm`
+//!
+//!   `import` statements in the generated file will have the `.js` extension in the end of
+//!   the path to conform to the ES Modules spec. (e.g.: `import { MyStruct } from "./my_struct.js"`)
 //!
 //! If there's a type you're dealing with which doesn't implement `TS`, use `#[ts(type = "..")]` or open a PR.
 //!

ts-rs/tests/imports.rs

@@ -31,6 +31,19 @@ fn test_def() {
     let text = std::fs::read_to_string(TestEnum::EXPORT_TO.unwrap()).unwrap();
 
     // Checks to make sure imports are ordered and deduplicated
+    #[cfg(feature = "import-esm")]
+    assert_eq!(text,
+        concat!(
+            "// This file was generated by [ts-rs](https://github.com/Aleph-Alpha/ts-rs). Do not edit this file manually.\n",
+            "import type { TestTypeA } from \"./ts_rs_test_type_a.js\";\n",
+            "import type { TestTypeB } from \"./ts_rs_test_type_b.js\";\n",
+            "\n",
+            "export type TestEnum = { \"C\": { value: TestTypeB<number> } } | {\n",
+            "  \"A1\": { value: TestTypeA<number> };\n",
+            "} | { \"A2\": { value: TestTypeA<number> } };\n"
+        )
+    );
+    #[cfg(not(feature = "import-esm"))]
     assert_eq!(text,
         concat!(
             "// This file was generated by [ts-rs](https://github.com/Aleph-Alpha/ts-rs). Do not edit this file manually.\n",