koajs

cors

CORS is a node.js package for providing a Connect/Express middleware that can be used to enable CORS with various options.

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NPM

build status

安装 (via npm)

$ npm install cors

使用

简单使用 (启用 All CORS 请求)

var express = require('express')
  , cors = require('cors')
  , app = express();

app.use(cors());

app.get('/products/:id', function(req, res, next){
  res.json({msg: 'This is CORS-enabled for all origins!'});
});

app.listen(80, function(){
  console.log('CORS-enabled web server listening on port 80');
});

启用单个路由 CORS

var express = require('express')
  , cors = require('cors')
  , app = express();

app.get('/products/:id', cors(), function(req, res, next){
  res.json({msg: 'This is CORS-enabled for all origins!'});
});

app.listen(80, function(){
  console.log('CORS-enabled web server listening on port 80');
});

配置 CORS

var express = require('express')
  , cors = require('cors')
  , app = express();

var corsOptions = {
  origin: 'http://example.com'
};

app.get('/products/:id', cors(corsOptions), function(req, res, next){
  res.json({msg: 'This is CORS-enabled for only example.com.'});
});

app.listen(80, function(){
  console.log('CORS-enabled web server listening on port 80');
});

配置 CORS w/ 动态源

var express = require('express')
  , cors = require('cors')
  , app = express();

var whitelist = ['http://example1.com', 'http://example2.com'];
var corsOptions = {
  origin: function(origin, callback){
    var originIsWhitelisted = whitelist.indexOf(origin) !== -1;
    callback(null, originIsWhitelisted);
  }
};

app.get('/products/:id', cors(corsOptions), function(req, res, next){
  res.json({msg: 'This is CORS-enabled for a whitelisted domain.'});
});

app.listen(80, function(){
  console.log('CORS-enabled web server listening on port 80');
});

启用预致 CORS

Certain CORS requests are considered 'complex' and require an initial OPTIONS request (called the "pre-flight request"). An example of a 'complex' CORS request is one that uses an HTTP verb other than GET/HEAD/POST (such as DELETE) or that uses custom headers. To enable pre-flighting, you must add a new OPTIONS handler for the route you want to support:

var express = require('express')
  , cors = require('cors')
  , app = express();

app.options('/products/:id', cors()); // enable pre-flight request for DELETE request
app.del('/products/:id', cors(), function(req, res, next){
  res.json({msg: 'This is CORS-enabled for all origins!'});
});

app.listen(80, function(){
  console.log('CORS-enabled web server listening on port 80');
});

You can also enable pre-flight across-the-board like so:

app.options('*', cors()); // include before other routes

配置 CORS 异步

var express = require('express')
  , cors = require('cors')
  , app = express();

var whitelist = ['http://example1.com', 'http://example2.com'];
var corsOptionsDelegate = function(req, callback){
  var corsOptions;
  if(whitelist.indexOf(req.header('Origin')) !== -1){
    corsOptions = { origin: true }; // reflect (enable) the requested origin in the CORS response
  }else{
    corsOptions = { origin: false }; // disable CORS for this request
  }
  callback(null, corsOptions); // callback expects two parameters: error and options
};

app.get('/products/:id', cors(corsOptionsDelegate), function(req, res, next){
  res.json({msg: 'This is CORS-enabled for a whitelisted domain.'});
});

app.listen(80, function(){
  console.log('CORS-enabled web server listening on port 80');
});

配置选项

  • origin: Configures the Access-Control-Allow-Origin CORS header. Expects a string (ex: "http://example.com"). Set to true to reflect the request origin, as defined by req.header('Origin'). Set to false to disable CORS. Can also be set to a function, which takes the request origin as the first parameter and a callback (which expects the signature err [object], allow [bool]) as the second.
  • methods: Configures the Access-Control-Allow-Methods CORS header. Expects a comma-delimited string (ex: 'GET,PUT,POST') or an array (ex: ['GET', 'PUT', 'POST']).
  • allowedHeaders: Configures the Access-Control-Allow-Headers CORS header. Expects a comma-delimited string (ex: 'Content-Type,Authorization') or an array (ex: ['Content-Type', 'Authorization]). If not specified, defaults to reflecting the headers specified in the request's Access-Control-Request-Headers header.
  • exposedHeaders: Configures the Access-Control-Expose-Headers CORS header. Expects a comma-delimited string (ex: 'Content-Range,X-Content-Range') or an array (ex: ['Content-Range', 'X-Content-Range]). If not specified, no custom headers are exposed.
  • credentials: Configures the Access-Control-Allow-Credentials CORS header. Set to true to pass the header, otherwise it is omitted.
  • maxAge: Configures the Access-Control-Allow-Max-Age CORS header. Set to an integer to pass the header, otherwise it is omitted.

For details on the effect of each CORS header, read this article on HTML5 Rocks.

演示

A demo that illustrates CORS working (and not working) using jQuery is available here: http://node-cors-client.herokuapp.com/

演示代码:

证书

MIT License

作者

Troy Goode (troygoode@gmail.com)