autodetect js module type - only bundle esm (#5515)

* wip: autodetect esm

* finish fixes

* thread minify through

* add sweetalert2

* Fix default bundle types

* ts-ignore

* small nits

* small more nits

* shrink flamegraph

packages/manganis/manganis-core/src/js.rs

@@ -22,6 +22,7 @@ pub struct JsAssetOptions {
     minify: bool,
     preload: bool,
     static_head: bool,
+    module: bool,
 }
 
 impl Default for JsAssetOptions {
@@ -42,6 +43,7 @@ impl JsAssetOptions {
             preload: false,
             minify: true,
             static_head: false,
+            module: false,
         }
     }
 
@@ -59,6 +61,11 @@ impl JsAssetOptions {
     pub const fn minified(&self) -> bool {
         self.minify
     }
+
+    /// Check whether the asset is declared as an ES module
+    pub const fn is_module(&self) -> bool {
+        self.module
+    }
 }
 
 impl AssetOptions {
@@ -116,6 +123,27 @@ impl AssetOptionsBuilder<JsAssetOptions> {
         self
     }
 
+    /// Mark the asset as an ES module (default: false)
+    ///
+    /// When true, the script tag emitted via `with_static_head(true)` is rendered as
+    /// `<script type="module" ...>`, and the file is delivered with its module syntax
+    /// (`import`/`export`) preserved so the browser can resolve imports natively at
+    /// runtime. The default treats the file as a classic script: `<script>` is emitted
+    /// without `type="module"`, and minification preserves classic-script semantics.
+    ///
+    /// Note: this does not perform build-time bundling. If you need imports resolved
+    /// into a single file, pre-bundle with your tool of choice and ship the result.
+    ///
+    /// ```rust
+    /// # use manganis::{asset, Asset, AssetOptions};
+    /// const _: Asset = asset!("/assets/script.js", AssetOptions::js().with_module(true));
+    /// ```
+    #[allow(unused)]
+    pub const fn with_module(mut self, module: bool) -> Self {
+        self.variant.module = module;
+        self
+    }
+
     /// Convert the builder into asset options with the given variant
     pub const fn into_asset_options(self) -> AssetOptions {
         AssetOptions {