javascript - 基本的node.js "function"与 "=>"表示法

Question

我必须修改基本 Node.js 文件上的代码才能使其正常工作，我想知道为什么？

失败:

const server = http.createServer((req, res) => {

这有效:

var server = http.createServer(function(req, res){

错误:

/my-app/tmp/hello2.js:6 var server = http.createServer((req, res) => { ^ SyntaxError: Unexpected token > at Module._compile (module.js:439:25) at Object.Module._extensions..js (module.js:474:10) at Module.load (module.js:356:32) at Function.Module._load (module.js:312:12) at Function.Module.runMain (module.js:497:10) at startup (node.js:119:16) at node.js:945:3

完整代码

const http = require('http');

const hostname = '127.0.0.1';
const port = 3000;

//const server = http.createServer((req, res) => {
// above *wont work*?? below works
var server = http.createServer(function(req, res){
  res.statusCode = 200;
  res.setHeader('Content-Type', 'text/plain');
  res.end('Hello World\n');
});

// server.listen(port, hostname, () => {
// above *wont work*?? below works
server.listen(port, hostname, function() {
  console.log(`Server running at http://${hostname}:${port}/`);
});

Answer 1

这是因为您的 Node.js 不支持 ES6 的某些标准功能

两种解决方案

1. 您必须编辑 package.json

   {
     "dependencies": {
     "babel-cli": "^6.0.0",
     "babel-preset-es2015": "^6.0.0"
    },
    "scripts": {
      "start": "babel-node --presets es2015 app.js"
    }
   }
   

   并运行npm start

   更多信息:How to run Node.js app with ES6 features enabled?

2. 更新您的 Node.js

   $ sudo npm cache clean -f
   $ sudo npm install -g n
   $ sudo n stable