問(wèn)題描述

data.js

var http=require(’http’);function runAsync(){ var p = new Promise(function(resolve, reject){//做一些異步操作 var json = ’’; http.get(’http://localhost:8080/getJson?’, function (res) {res.on(’data’, function (data) {json += data;}).on(’end’,function (){ json = JSON.parse(json); resolve(json); })}).on(’error’, function (e) { console.error(e); }); }); return p;}**module.exports=runAsync().then(function(data){ console.log(data); return data;});**//注意這句，我明明返回的是runasync.then(。。。。）為什么他給我返回了runasync()

index.js

var express = require(’express’);var router = express.Router();var getdata=require(’../serve/data.js’);/* GET home page. */router.get(’/’, function(req, res, next) { //var a=JSON.parse(getdata); console.log(getdata); res.render(’index’,{title:getdata.total});});module.exports = router;

結(jié)果：

問(wèn)題解答

Promise.prototype.then()

無(wú)論什么時(shí)候返回的都是另外一個(gè)Promise對(duì)象，then()方法接受的參數(shù)是回調(diào)函數(shù)，你只能控制回調(diào)函數(shù)的返回值，不能控制then()方法的返回值。手機(jī)打字不方便，有疑問(wèn)的話，等我用電腦回答。

var express = require(’express’);var router = express.Router();var data=require(’../serve/data.js’);/* GET home page. */router.get(’/’, function(req, res, next) { //var a=JSON.parse(getdata); data.then(function(data){console.log(data.total);res.render(’index’,{title:data.total}); }); });module.exports = router;

這樣寫就行