fix(es/loader): Prefer ESM (#3089)

swc_ecma_loader: - Check for `module` field and prefer it over `main`.
swc-project · Dec 21, 2021 · ba2563f · ba2563f · github-actions · Dec 21, 2021
1 parent e33248c
commit ba2563f
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Showing 2 changed files with 11 additions and 5 deletions.
diff --git a/crates/swc_bundler/examples/bundle.rs b/crates/swc_bundler/examples/bundle.rs
@@ -81,7 +81,7 @@ fn do_test(_entry: &Path, entries: HashMap<String, FileName>, inline: bool, mini
                 NodeModulesResolver::new(TargetEnv::Node, Default::default()),
             ),
             swc_bundler::Config {
-                require: true,
+                require: false,
                 disable_inliner: !inline,
                 external_modules: Default::default(),
                 disable_fixer: minify,

diff --git a/crates/swc_ecma_loader/src/resolvers/node.rs b/crates/swc_ecma_loader/src/resolvers/node.rs
@@ -61,6 +61,8 @@ struct PackageJson {
     main: Option<String>,
     #[serde(default)]
     browser: Option<Browser>,
+    #[serde(default)]
+    module: Option<String>,
 }
 
 #[derive(Deserialize)]
@@ -178,13 +180,17 @@ impl NodeModulesResolver {
 
         let main_fields = match self.target_env {
             TargetEnv::Node => {
-                vec![pkg.main.as_ref().clone()]
+                vec![pkg.module.as_ref().clone(), pkg.main.as_ref().clone()]
             }
             TargetEnv::Browser => {
                 if let Some(browser) = &pkg.browser {
                     match browser {
                         Browser::Str(path) => {
-                            vec![Some(path), pkg.main.as_ref().clone()]
+                            vec![
+                                Some(path),
+                                pkg.module.as_ref().clone(),
+                                pkg.main.as_ref().clone(),
+                            ]
                         }
                         Browser::Obj(map) => {
                             let bucket = BROWSER_CACHE.entry(pkg_dir.to_path_buf()).or_default();
@@ -237,11 +243,11 @@ impl NodeModulesResolver {
                                     }
                                 }
                             }
-                            vec![pkg.main.as_ref().clone()]
+                            vec![pkg.module.as_ref().clone(), pkg.main.as_ref().clone()]
                         }
                     }
                 } else {
-                    vec![pkg.main.as_ref().clone()]
+                    vec![pkg.module.as_ref().clone(), pkg.main.as_ref().clone()]
                 }
             }
         };
Benchmark suite	Current: `ba2563f`	Previous: `c9def54`	Ratio
`full_es2015`	`216390385` ns/iter (`± 14649968`)	`183588506` ns/iter (`± 5371293`)	`1.18`
`full_es2016`	`185160047` ns/iter (`± 13503985`)	`151987907` ns/iter (`± 5383572`)	`1.22`
`full_es2017`	`187724716` ns/iter (`± 19813565`)	`156324968` ns/iter (`± 6411452`)	`1.20`
`full_es2018`	`172649718` ns/iter (`± 13651751`)	`156154979` ns/iter (`± 3731519`)	`1.11`
`full_es2019`	`171821453` ns/iter (`± 15037310`)	`153621108` ns/iter (`± 7532837`)	`1.12`
`full_es2020`	`172426342` ns/iter (`± 14886998`)	`153010972` ns/iter (`± 4934926`)	`1.13`
`full_es3`	`237646080` ns/iter (`± 20946292`)	`209931878` ns/iter (`± 9927739`)	`1.13`
`full_es5`	`217306388` ns/iter (`± 16446117`)	`195006307` ns/iter (`± 10438175`)	`1.11`
`parser`	`791618` ns/iter (`± 118346`)	`682190` ns/iter (`± 19054`)	`1.16`