don't await non-objects returned from functions passed to AsyncIterator helpers

tc39/proposal-iterator-helpers#239

Author: zloirock

CHANGELOG.md

@@ -8,6 +8,7 @@
   - `String.prototype.toWellFormed`
 - Recent updates of the [iterator helpers proposal](https://github.com/tc39/proposal-iterator-helpers):
   - Added a counter parameter to helpers, [proposal-iterator-helpers/211](https://github.com/tc39/proposal-iterator-helpers/pull/211)
+  - Don't await non-objects returned from functions passed to `AsyncIterator` helpers, [proposal-iterator-helpers/239](https://github.com/tc39/proposal-iterator-helpers/pull/239)
   - Early exit on broken `.next` in missed cases of `{ Iterator, AsyncIterator }.from`, [proposal-iterator-helpers/232](https://github.com/tc39/proposal-iterator-helpers/pull/232)
 - Added `inverse` option to `core-js-compat`, [#1119](https://github.com/zloirock/core-js/issues/1119)
 - Added `format` option to `core-js-builder`, [#1120](https://github.com/zloirock/core-js/issues/1120)

packages/core-js/internals/async-iterator-iteration.js

@@ -4,6 +4,7 @@
 var call = require('../internals/function-call');
 var aCallable = require('../internals/a-callable');
 var anObject = require('../internals/an-object');
+var isObject = require('../internals/is-object');
 var doesNotExceedSafeInteger = require('../internals/does-not-exceed-safe-integer');
 var getBuiltIn = require('../internals/get-built-in');
 var getIteratorDirect = require('../internals/get-iterator-direct');
@@ -44,20 +45,25 @@ var createMethod = function (TYPE) {
                 var value = step.value;
                 try {
                   if (MAPPING) {
-                    Promise.resolve(fn(value, counter)).then(function (result) {
+                    var result = fn(value, counter);
+
+                    var handler = function ($result) {
                       if (IS_FOR_EACH) {
                         loop();
                       } else if (IS_EVERY) {
-                        result ? loop() : closeAsyncIteration(iterator, resolve, false, reject);
+                        $result ? loop() : closeAsyncIteration(iterator, resolve, false, reject);
                       } else if (IS_TO_ARRAY) {
                         try {
-                          target[counter++] = result;
+                          target[counter++] = $result;
                           loop();
                         } catch (error4) { ifAbruptCloseAsyncIterator(error4); }
                       } else {
-                        result ? closeAsyncIteration(iterator, resolve, IS_SOME || value, reject) : loop();
+                        $result ? closeAsyncIteration(iterator, resolve, IS_SOME || value, reject) : loop();
                       }
-                    }, ifAbruptCloseAsyncIterator);
+                    };
+
+                    if (isObject(result)) Promise.resolve(result).then(handler, ifAbruptCloseAsyncIterator);
+                    else handler(result);
                   } else {
                     target[counter++] = value;
                     loop();

packages/core-js/modules/esnext.async-iterator.filter.js

@@ -4,6 +4,7 @@ var $ = require('../internals/export');
 var call = require('../internals/function-call');
 var aCallable = require('../internals/a-callable');
 var anObject = require('../internals/an-object');
+var isObject = require('../internals/is-object');
 var getIteratorDirect = require('../internals/get-iterator-direct');
 var createAsyncIteratorProxy = require('../internals/async-iterator-create-proxy');
 var createIterResultObject = require('../internals/create-iter-result-object');
@@ -34,9 +35,14 @@ var AsyncIteratorProxy = createAsyncIteratorProxy(function (Promise) {
             } else {
               var value = step.value;
               try {
-                Promise.resolve(filterer(value, state.counter++)).then(function (selected) {
+                var result = filterer(value, state.counter++);
+
+                var handler = function (selected) {
                   selected ? resolve(createIterResultObject(value, false)) : loop();
-                }, ifAbruptCloseAsyncIterator);
+                };
+
+                if (isObject(result)) Promise.resolve(result).then(handler, ifAbruptCloseAsyncIterator);
+                else handler(result);
               } catch (error3) { ifAbruptCloseAsyncIterator(error3); }
             }
           } catch (error2) { doneAndReject(error2); }

packages/core-js/modules/esnext.async-iterator.flat-map.js

@@ -4,6 +4,7 @@ var $ = require('../internals/export');
 var call = require('../internals/function-call');
 var aCallable = require('../internals/a-callable');
 var anObject = require('../internals/an-object');
+var isObject = require('../internals/is-object');
 var getIteratorDirect = require('../internals/get-iterator-direct');
 var createAsyncIteratorProxy = require('../internals/async-iterator-create-proxy');
 var createIterResultObject = require('../internals/create-iter-result-object');
@@ -36,13 +37,18 @@ var AsyncIteratorProxy = createAsyncIteratorProxy(function (Promise) {
             } else {
               var value = step.value;
               try {
-                Promise.resolve(mapper(value, state.counter++)).then(function (mapped) {
+                var result = mapper(value, state.counter++);
+
+                var handler = function (mapped) {
                   try {
                     state.innerIterator = innerIterator = getAsyncIterator(mapped);
                     state.innerNext = aCallable(innerIterator.next);
                     innerLoop();
                   } catch (error4) { ifAbruptCloseAsyncIterator(error4); }
-                }, ifAbruptCloseAsyncIterator);
+                };
+
+                if (isObject(result)) Promise.resolve(result).then(handler, ifAbruptCloseAsyncIterator);
+                else handler(result);
               } catch (error3) { ifAbruptCloseAsyncIterator(error3); }
             }
           } catch (error2) { doneAndReject(error2); }

packages/core-js/modules/esnext.async-iterator.map.js

@@ -4,6 +4,7 @@ var $ = require('../internals/export');
 var call = require('../internals/function-call');
 var aCallable = require('../internals/a-callable');
 var anObject = require('../internals/an-object');
+var isObject = require('../internals/is-object');
 var getIteratorDirect = require('../internals/get-iterator-direct');
 var createAsyncIteratorProxy = require('../internals/async-iterator-create-proxy');
 var createIterResultObject = require('../internals/create-iter-result-object');
@@ -32,9 +33,14 @@ var AsyncIteratorProxy = createAsyncIteratorProxy(function (Promise) {
         } else {
           var value = step.value;
           try {
-            Promise.resolve(mapper(value, state.counter++)).then(function (mapped) {
+            var result = mapper(value, state.counter++);
+
+            var handler = function (mapped) {
               resolve(createIterResultObject(mapped, false));
-            }, ifAbruptCloseAsyncIterator);
+            };
+
+            if (isObject(result)) Promise.resolve(result).then(handler, ifAbruptCloseAsyncIterator);
+            else handler(result);
           } catch (error2) { ifAbruptCloseAsyncIterator(error2); }
         }
       } catch (error) { doneAndReject(error); }

packages/core-js/modules/esnext.async-iterator.reduce.js

@@ -4,6 +4,7 @@ var $ = require('../internals/export');
 var call = require('../internals/function-call');
 var aCallable = require('../internals/a-callable');
 var anObject = require('../internals/an-object');
+var isObject = require('../internals/is-object');
 var getBuiltIn = require('../internals/get-built-in');
 var getIteratorDirect = require('../internals/get-iterator-direct');
 var closeAsyncIteration = require('../internals/async-iterator-close');
@@ -39,10 +40,15 @@ $({ target: 'AsyncIterator', proto: true, real: true, forced: true }, {
                   accumulator = value;
                   loop();
                 } else try {
-                  Promise.resolve(reducer(accumulator, value, counter)).then(function (result) {
-                    accumulator = result;
+                  var result = reducer(accumulator, value, counter);
+
+                  var handler = function ($result) {
+                    accumulator = $result;
                     loop();
-                  }, ifAbruptCloseAsyncIterator);
+                  };
+
+                  if (isObject(result)) Promise.resolve(result).then(handler, ifAbruptCloseAsyncIterator);
+                  else handler(result);
                 } catch (error3) { ifAbruptCloseAsyncIterator(error3); }
               }
               counter++;