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Async Generators doesn't polyfilled correctly by metro-react-native-babel-preset #842

@retyui

Description

@retyui

Do you want to request a feature or report a bug?

MDN: Async Generators

async function* asyncGenerator() {
  let i = 0;
  while (i < 3) {
    yield i++;
  }
}

(async () => {
  for await (const num of asyncGenerator()) {
    console.log(num);
  }
})();
JS Output...
function _createForOfIteratorHelperLoose(o, allowArrayLike) { var it = typeof Symbol !== "undefined" && o[Symbol.iterator] || o["@@iterator"]; if (it) return (it = it.call(o)).next.bind(it); if (Array.isArray(o) || (it = _unsupportedIterableToArray(o)) || allowArrayLike && o && typeof o.length === "number") { if (it) o = it; var i = 0; return function () { if (i >= o.length) return { done: true }; return { done: false, value: o[i++] }; }; } throw new TypeError("Invalid attempt to iterate non-iterable instance.\nIn order to be iterable, non-array objects must have a [Symbol.iterator]() method."); }

function _unsupportedIterableToArray(o, minLen) { if (!o) return; if (typeof o === "string") return _arrayLikeToArray(o, minLen); var n = Object.prototype.toString.call(o).slice(8, -1); if (n === "Object" && o.constructor) n = o.constructor.name; if (n === "Map" || n === "Set") return Array.from(o); if (n === "Arguments" || /^(?:Ui|I)nt(?:8|16|32)(?:Clamped)?Array$/.test(n)) return _arrayLikeToArray(o, minLen); }

function _arrayLikeToArray(arr, len) { if (len == null || len > arr.length) len = arr.length; for (var i = 0, arr2 = new Array(len); i < len; i++) { arr2[i] = arr[i]; } return arr2; }

var _marked = _$$_REQUIRE(_dependencyMap[0], "@babel/runtime/regenerator").mark(asyncGenerator);

function asyncGenerator() {
  var i;
  return _$$_REQUIRE(_dependencyMap[0], "@babel/runtime/regenerator").async(function asyncGenerator$(_context) {
    while (1) {
      switch (_context.prev = _context.next) {
        case 0:
          i = 0;

        case 1:
          if (!(i < 3)) {
            _context.next = 6;
            break;
          }

          _context.next = 4;
          return i++;

        case 4:
          _context.next = 1;
          break;

        case 6:
        case "end":
          return _context.stop();
      }
    }
  }, _marked, null, null, Promise);
}

(function _callee() {
  var _iterator, _step, num;

  return _$$_REQUIRE(_dependencyMap[0], "@babel/runtime/regenerator").async(function _callee$(_context2) {
    while (1) {
      switch (_context2.prev = _context2.next) {
        case 0:
          for (_iterator = _createForOfIteratorHelperLoose(asyncGenerator()); !(_step = _iterator()).done;) {
            num = _step.value;
            console.log(num);
          }

        case 1:
        case "end":
          return _context2.stop();
      }
    }
  }, null, null, null, Promise);
})();

What is the current behavior?

// output
TypeError: Invalid attempt to iterate non-iterable instance.
In order to be iterable, non-array objects must have a [Symbol.iterator]() method.

What is the expected behavior?

// output
0
1
2

Please provide your exact Metro configuration and mention your Metro, node, yarn/npm version and operating system.

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