module: be lazy when creating CJS facades

bmeck · addaleax · commit 221985967574 · 2017-11-28T02:52:43.000+01:00
This should remove the penalty for loading CJS that is never imported. PR-URL: nodejs#17153 Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com> Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com> Reviewed-By: Colin Ihrig <cjihrig@gmail.com> Reviewed-By: Timothy Gu <timothygu99@gmail.com> Reviewed-By: James M Snell <jasnell@gmail.com>
diff --git a/lib/module.js b/lib/module.js
@@ -575,15 +575,21 @@ Module.prototype.load = function(filename) {
   if (ESMLoader) {
     const url = getURLFromFilePath(filename);
     const urlString = `${url}`;
+    const exports = this.exports;
     if (ESMLoader.moduleMap.has(urlString) !== true) {
-      const ctx = createDynamicModule(['default'], url);
-      ctx.reflect.exports.default.set(this.exports);
-      ESMLoader.moduleMap.set(urlString,
-                              new ModuleJob(ESMLoader, url, async () => ctx));
+      ESMLoader.moduleMap.set(
+        urlString,
+        new ModuleJob(ESMLoader, url, async () => {
+          const ctx = createDynamicModule(
+            ['default'], url);
+          ctx.reflect.exports.default.set(exports);
+          return ctx;
+        })
+      );
     } else {
       const job = ESMLoader.moduleMap.get(urlString);
       if (job.reflect)
-        job.reflect.exports.default.set(this.exports);
+        job.reflect.exports.default.set(exports);
     }
   }
 };
