如何在node.js的express.js框架中启用跨域资源共享（CORS）

Question

我正在尝试在node.js中构建一个Web服务器，该服务器将支持跨域脚本编写，同时仍从公共目录中提供静态文件。我正在使用express.js，但不确定如何允许跨域脚本（Access- Control-Allow-Origin: *）。

var express = require('express')
  , app = express.createServer();

app.get('/', function (req, res, next) {
    res.header("Access-Control-Allow-Origin", "*");
    res.header("Access-Control-Allow-Headers", "X-Requested-With");
    next();
});

app.configure(function () {
    app.use(express.methodOverride());
    app.use(express.bodyParser());
    app.use(app.router);
});

app.configure('development', function () {

    app.use(express.static(__dirname + '/public'));
    app.use(express.errorHandler({ dumpExceptions: true, showStack: true }));
});

app.configure('production', function () {


    var oneYear = 31557600000;
    //    app.use(express.static(__dirname + '/public', { maxAge: oneYear }));
    app.use(express.static(__dirname + '/public'));
    app.use(express.errorHandler());
});

app.listen(8888);
console.log('express running at http://localhost:%d', 8888);

Answer 1

查看来自enable-cors.org的示例：

在node.js上的ExpressJS应用中，对路由执行以下操作：

app.all('/', function(req, res, next) {
  res.header("Access-Control-Allow-Origin", "*");
  res.header("Access-Control-Allow-Headers", "X-Requested-With");
  next();
 });

app.get('/', function(req, res, next) {
  // Handle the get for this route
});

app.post('/', function(req, res, next) {
 // Handle the post for this route
});

首次呼叫（app.all）应该在应用中的所有其他路由（或至少要启用CORS的路由）之前进行。

[编辑]

如果您还希望显示静态文件的标头，请尝试执行此操作（确保在调用之前use(express.static())：

app.use(function(req, res, next) {
  res.header("Access-Control-Allow-Origin", "*");
  res.header("Access-Control-Allow-Headers", "X-Requested-With");
  next();
});

我用您的代码对此进行了测试，并从public目录中获取了资产的标头：

var express = require('express')
  , app = express.createServer();

app.configure(function () {
    app.use(express.methodOverride());
    app.use(express.bodyParser());
    app.use(function(req, res, next) {
      res.header("Access-Control-Allow-Origin", "*");
      res.header("Access-Control-Allow-Headers", "X-Requested-With");
      next();
    });
    app.use(app.router);
});

app.configure('development', function () {
    app.use(express.static(__dirname + '/public'));
    app.use(express.errorHandler({ dumpExceptions: true, showStack: true }));
});

app.configure('production', function () {
    app.use(express.static(__dirname + '/public'));
    app.use(express.errorHandler());
});

app.listen(8888);
console.log('express running at http://localhost:%d', 8888);

当然，您可以将该功能打包到一个模块中，以便可以执行以下操作

// cors.js

module.exports = function() {
  return function(req, res, next) {
    res.header("Access-Control-Allow-Origin", "*");
    res.header("Access-Control-Allow-Headers", "X-Requested-With");
    next();
  };
}

// server.js

cors = require('./cors');
app.use(cors());