avoid unnecessary promise creation and do not validate result in `%Wr…

…apForValid(Async)IteratorPrototype%.return` tc39/proposal-iterator-helpers#215
zloirock · Aug 10, 2022 · 9ca5a51 · 9ca5a51
1 parent 8685d52
commit 9ca5a51
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -1,5 +1,6 @@
 ## Changelog
 ##### Unreleased
+- Avoid unnecessary promise creation and do not validate result in `%WrapForValid(Async)IteratorPrototype%.return`, [proposal-iterator-helpers/215](https://github.com/tc39/proposal-iterator-helpers/pull/215)
 - Relaxed condition of re-usage native `WeakMap` for internal states with multiple `core-js` copies
 - Some stylistic changes
 - Added Electron 21 compat data mapping

diff --git a/packages/core-js/internals/async-iterator-create-proxy.js b/packages/core-js/internals/async-iterator-create-proxy.js
@@ -76,21 +76,29 @@ var createAsyncIteratorProxyPrototype = function (IS_ITERATOR) {
       var state = stateCompletion.value;
 
       return exit ? state : enqueue(state, function () {
-        return new Promise(function (resolve, reject) {
-          var iterator = state.iterator;
-          var innerIterator = state.innerIterator;
-          state.done = true;
+        state.done = true;
+        var iterator = state.iterator;
+        var innerIterator = state.innerIterator;
+        var returnMethod, result;
+        var completion = perform(function () {
           if (innerIterator) try {
             iteratorClose(innerIterator, 'return');
           } catch (error) {
             return iteratorClose(iterator, 'throw', error);
           }
-          var $$return = getMethod(iterator, 'return');
-          if ($$return === undefined) return resolve({ done: true, value: undefined });
-          Promise.resolve(call($$return, iterator)).then(function (result) {
-            anObject(result);
-            resolve({ done: true, value: undefined });
-          }, reject);
+          return getMethod(iterator, 'return');
+        });
+        returnMethod = result = completion.value;
+        if (completion.error) return Promise.reject(result);
+        if (returnMethod === undefined) return Promise.resolve({ value: undefined, done: true });
+        completion = perform(function () {
+          return call(returnMethod, iterator);
+        });
+        result = completion.value;
+        if (completion.error) return Promise.reject(result);
+        return IS_ITERATOR ? Promise.resolve(result) : Promise.resolve(result).then(function (resolved) {
+          anObject(resolved);
+          return { value: undefined, done: true };
         });
       });
     }

diff --git a/packages/core-js/internals/iterator-create-proxy.js b/packages/core-js/internals/iterator-create-proxy.js
@@ -46,8 +46,9 @@ var createIteratorProxyPrototype = function (IS_ITERATOR) {
       } catch (error) {
         return iteratorClose(iterator, 'throw', error);
       }
-      var $$return = getMethod(iterator, 'return');
-      return { done: true, value: $$return ? anObject(call($$return, iterator)).value : undefined };
+      var returnMethod = getMethod(iterator, 'return');
+      var result = returnMethod && call(returnMethod, iterator);
+      return IS_ITERATOR && returnMethod ? result : { value: returnMethod ? anObject(result).value : undefined, done: true };
     }
   });