function asyncFn(callback) {
 // 利用setTimeout模拟异步
 setTimeout(function () {
  console.log('执行完毕');
  callback(); // 发通知
 }, 2000);
}

asyncFn(function () {
 console.log('我会在2s后输出');
});

function asyncFn() {
 return new Promise((resolve, reject) => {
  // 利用setTimeout模拟异步
  setTimeout(function () {
   console.log('执行完毕');
   resolve(); // 发通知（是否有感觉到回调的影子？）
  }, 2000);
 });
}

asyncFn()
 .then(function () {
  console.log('我会在2s后输出');
 });

function asyncFn() {
 return new Promise((resolve, reject) => {
  // 利用setTimeout模拟异步
  setTimeout(function () {
   console.log('执行完毕');
   resolve(); // 发通知（是否有感觉到回调的影子？）
  }, 2000);
 });
}

function* generatorSync() {
 var result = yield asyncFn();
}

var g = generatorSync();
g.next().value.then(()=>{
 console.log('我会在2s后输出');
});

function asyncFn() {
 return new Promise((resolve, reject) => {
  // 利用setTimeout模拟异步
  setTimeout(function () {
   console.log('执行完毕');
   resolve(); // 发通知（是否有感觉到回调的影子？）
  }, 2000);
 });
}

async function run(){
 await asyncFn();
 console.log('我会在2s后输出');
}

run();

var express = require('express');
var router = express.Router();

/* GET home page. */
router.get('/', function(req, res, next) {
 res.render('index', { title: 'Express' });
});

module.exports = router;

var express = require('express');
var router = express.Router();

function asyncFn(req, res, next) {
 setTimeout(() => {
  req.user = {}; // 设置当前请求的用户
  next();
 }, 2000);
}

function asyncFn2(req, res, next) {
 setTimeout(() => {
  req.auth = {}; // 设置用户权限
  next();
 }, 2000);
}

function asyncFn3(req, res, next) {
 setTimeout(() => {
  res.locals = { title: 'Express Async Test' }; // 设置数据
  res.render('index'); // 响应
 }, 2000);
}

/* GET home page. */
router.get('/', asyncFn, asyncFn2, asyncFn3); // 一步步执行中间件

module.exports = router;

var express = require('express');
var router = express.Router();

function asyncFn(req, res) {
 return new Promise((resolve, reject) => {
  setTimeout(() => {
   req.user = {}; // 设置当前请求的用户
   resolve(req);
  }, 2000);
 });
}

function asyncFn2(req) {
 return new Promise((resolve, reject) => {
  setTimeout(() => {
   req.auth = {}; // 设置用户权限
   resolve();
  }, 2000);
 });
}

function asyncFn3(res) {
 return new Promise((resolve, reject) => {
  setTimeout(() => {
   res.locals = { title: 'Express Async Test' }; // 设置数据
   res.render('index'); // 响应
  }, 2000);
 });
}

function doBizAsync(req, res, next) {
 asyncFn(req)
  .then(() => asyncFn2(req))
  .then(() => asyncFn3(res))
  .catch(next); // 统一异常处理
};

/* GET home page. */
router.get('/', doBizAsync);

module.exports = router;

var express = require('express');
var router = express.Router();

function asyncFn(req) {
 return new Promise((resolve, reject) => {
  setTimeout(() => {
   req.user = {}; // 设置当前请求的用户
   resolve(req);
  }, 2000);
 });
}

function asyncFn2(req) {
 return new Promise((resolve, reject) => {
  setTimeout(() => {
   req.auth = {}; // 设置用户权限
   resolve();
  }, 2000);
 });
}

function asyncFn3(res) {
 return new Promise((resolve, reject) => {
  setTimeout(() => {

  }, 2000);
 });
}

async function doBizAsync(req, res, next) {
 var result = await asyncFn(req);
 var result2 = await asyncFn2(req);
 res.locals = { title: 'Express Async Test' }; // 设置数据
 res.render('index'); // 响应
};

const tools = {
 asyncWrap(fn) {
  return (req, res, next) => {
   fn(req, res, next).catch(next); // async...await在Express中的错误处理
  }
 }
};

/* GET home page. */
router.get('/', tools.asyncWrap(doBizAsync)); // 需要用工具方法包裹一下

module.exports = router;