在Node.js中使用TypeScriptasynchronous等待
我发现不可能完成接下来的四件事情：
- 在Node.js中编写
- 在TypeScript中编写
- 使用
async await - debugging容易
说明：
我有一个在TypeScript中编写的Node.js项目，我正在使用async await 。
现在的问题是，如果我transpile到ES6，导入关键字会产生“意外的令牌导入”错误在这里讨论： ES6导入和导出不支持在Node.js ，而如果我transpile到ES5， async await变成不可读码：
这个：
///<reference path="../typings/modules/bluebird/index.d.ts" /> ///<reference path="../typings/modules/mongodb/index.d.ts" /> import * as Promise from 'bluebird'; import { MongoClient, Db } from 'mongodb'; import {Campaign} from "../classes/Campaign"; export async function getCampaigns(): Campaign[] { try{ var db = await connect(); var campaigns: Campaign[] = await db.collection("campaigns").find().toArray(); return campaigns; } catch (err){ console.log(err); } } async function connect(): Promise<Db> { return await MongoClient.connect("mongodb://localhost:27017/db"); }
变成这样：
"use strict"; 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; return { next: verb(0), "throw": verb(1), "return": verb(2) }; 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 = y[op[0] & 2 ? "return" : op[0] ? "throw" : "next"]) && !(t = t.call(y, op[1])).done) return t; if (y = 0, t) op = [0, 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 }; } }; ///<reference path="../typings/modules/bluebird/index.d.ts" /> ///<reference path="../typings/modules/mongodb/index.d.ts" /> var Promise = require("bluebird"); var mongodb_1 = require("mongodb"); function getCampaigns() { return __awaiter(this, void 0, void 0, function () { var db, campaigns, err_1; return __generator(this, function (_a) { switch (_a.label) { case 0: _a.trys.push([0, 3, , 4]); return [4 /*yield*/, connect()]; case 1: db = _a.sent(); return [4 /*yield*/, db.collection("campaigns").find().toArray()]; case 2: campaigns = _a.sent(); return [2 /*return*/, campaigns]; case 3: err_1 = _a.sent(); console.log(err_1); return [3 /*break*/, 4]; case 4: return [2 /*return*/]; } }); }); } exports.getCampaigns = getCampaigns; function connect() { return __awaiter(this, void 0, Promise, function () { return __generator(this, function (_a) { switch (_a.label) { case 0: return [4 /*yield*/, mongodb_1.MongoClient.connect("mongodb://localhost:27017/db")]; case 1: return [2 /*return*/, _a.sent()]; } }); }); }
我怎样才能解决这个悖论？
如果我传递给ES6，导入关键字会产生“意外令牌导入”错误
实际上有两个解决scheme。 select其中之一或组合：
- 始终使用
import / require而不是ES6导入 - 指定
--module commonjs
保持目标和ES6，享受:)