optimize: builtins.intersectAttrs

nix-js/runtime-ts/src/builtins/attrs.ts

@@ -72,9 +72,21 @@ export const intersectAttrs =
     const f1 = forceAttrs(e1);
     const f2 = forceAttrs(e2);
     const attrs: NixAttrs = {};
-    for (const key of Object.keys(f2)) {
-      if (Object.hasOwn(f1, key)) {
-        attrs[key] = f2[key];
+    const k1 = Object.keys(f1);
+    const k2 = Object.keys(f2);
+    if (k1.length < k2.length) {
+      for (let i = 0; i < k1.length; i++) {
+        const key = k1[i];
+        if (key in f2) {
+          attrs[key] = f2[key];
+        }
+      }
+    } else {
+      for (let i = 0; i < k2.length; i++) {
+        const key = k2[i];
+        if (key in f1) {
+          attrs[key] = f2[key];
+        }
       }
     }
     return attrs;