fix: copy function in instance

.gitignore

@@ -19,6 +19,9 @@ lib-cov
 # Coverage directory used by tools like istanbul
 coverage
 
+# idea
+.idea
+
 # nyc test coverage
 .nyc_output
 

src/collection.ts

@@ -55,7 +55,13 @@ export function getKeys(
       return ([] as Array<string | symbol>).concat(
         // NOTE: Object.getOwnPropertyNames can get all own keys.
         Object.keys(collection as Record<string, unknown>),
-        Object.getOwnPropertySymbols(collection as Record<symbol, unknown>)
+        Object.getOwnPropertySymbols(collection as Record<symbol, unknown>),
+        (collection as any).__proto__.constructor ===
+          Object.prototype.constructor
+          ? []
+          : Object.getOwnPropertyNames(
+              Object.getPrototypeOf(collection)
+            ).filter((key) => key !== 'constructor')
       );
     case typeMap:
     case typeSet:

test/index.ts

@@ -586,6 +586,24 @@ describe('deepcopy', function () {
         assert((result.get(3) || {}).b === 8);
         assert((result.get(3) || {}).c === 9);
       });
+
+      it('function in class', function () {
+        class Test {
+          fn() {
+            return this;
+          }
+        }
+
+        const origin = { inside: new Test() };
+        const result = deepcopy(origin);
+        assert(typeof result.inside.fn === 'function');
+      });
+
+      it('function in Object', function () {
+        const origin = { fn: () => console.log('function') };
+        const result = deepcopy(origin);
+        assert(typeof result.fn === 'function');
+      });
     });
   });