使用Promise时，Typescript生成__awaiter，__ generator

Question

我正在尝试使用nodejs的Promise，我的nodejs版本是10.15.3。 我可以运行此代码，但是当我尝试将其翻译为打字稿时，它的工作方式却很奇怪

const p = async () => {
    return new Promise((resolve, reject) => {
        resolve("Promise works!")
    })
}

async function main() {
    await p().then(res => console.log(res))
}

main()

这是打字稿编译器的输出：

var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, generator) {
    return new (P || (P = Promise))(function (resolve, reject) {
        function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
        function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
        function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); }
        step((generator = generator.apply(thisArg, _arguments || [])).next());
    });
};
var __generator = (this && this.__generator) || function (thisArg, body) {
    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
    function verb(n) { return function (v) { return step([n, v]); }; }
    function step(op) {
        if (f) throw new TypeError("Generator is already executing.");
        while (_) try {
            if (f = 1, y && (t = op[0] & 2 ? y["return"] : op[0] ? y["throw"] || ((t = y["return"]) && t.call(y), 0) : y.next) && !(t = t.call(y, op[1])).done) return t;
            if (y = 0, t) op = [op[0] & 2, t.value];
            switch (op[0]) {
                case 0: case 1: t = op; break;
                case 4: _.label++; return { value: op[1], done: false };
                case 5: _.label++; y = op[1]; op = [0]; continue;
                case 7: op = _.ops.pop(); _.trys.pop(); continue;
                default:
                    if (!(t = _.trys, t = t.length > 0 && t[t.length - 1]) && (op[0] === 6 || op[0] === 2)) { _ = 0; continue; }
                    if (op[0] === 3 && (!t || (op[1] > t[0] && op[1] < t[3]))) { _.label = op[1]; break; }
                    if (op[0] === 6 && _.label < t[1]) { _.label = t[1]; t = op; break; }
                    if (t && _.label < t[2]) { _.label = t[2]; _.ops.push(op); break; }
                    if (t[2]) _.ops.pop();
                    _.trys.pop(); continue;
            }
            op = body.call(thisArg, _);
        } catch (e) { op = [6, e]; y = 0; } finally { f = t = 0; }
        if (op[0] & 5) throw op[1]; return { value: op[0] ? op[1] : void 0, done: true };
    }
};
var _this = this;
var p = function () { return __awaiter(_this, void 0, void 0, function () {
    return __generator(this, function (_a) {
        return [2 /*return*/, new Promise(function (resolve, reject) {
                resolve("Promise works!");
            })];
    });
}); };
function main() {
    return __awaiter(this, void 0, void 0, function () {
        return __generator(this, function (_a) {
            switch (_a.label) {
                case 0: return [4 /*yield*/, p().then(function (res) { return console.log(res); })];
                case 1:
                    _a.sent();
                    return [2 /*return*/];
            }
        });
    });
}
main();

为什么打字稿会创建__awaiter和__generator？我的tsconfig.json看起来像这样：

{
    "compilerOptions": {
        "target": "es6",
        "module": "commonjs",
        "allowSyntheticDefaultImports": true,
        "esModuleInterop": true,    
        "noEmitOnError": true,
        "importHelpers": true
    },
    "exclude": [
        "node_modules",
        "**/*.spec.ts"
    ]
}

更新： 打字稿版本^3.4.5 我不使用纯粹的tsc编译器webpack