NodeJS实现跨域的方法(使用示例)

//引用express 
    const express = require('express') 
    //设置实例，调用express方法 
    const app = express()    
    //设置跨域 
    app.all("*",(req,res,next)=>{ 
        res.header("Access-Control-Allow-Origin","*") 
        res.header("Access-Control-Allow-Headers","Content-Type") 
        res.header("Access-Control-Allow-Methods","*") 
        res.header('Content-Type','application/json;charset=utf-8') 
        next() 
    }) 

var express = require('express') 
var cors = require('cors') 
var app = express() 
app.use(cors())  
app.get('/products/:id', function (req, res, next) { 
  res.json({msg: '这对所有来源都启用了 CORS！'}) 
})   
app.listen(80, function () { 
  console.log('CORS-enabled web server listening on port 80') 
}) 

var express = require('express') 
var cors = require('cors') 
var app = express() 
var corsOptions = { 
  origin: 'http://example.com', 
  optionsSuccessStatus: 200 // some legacy browsers (IE11, various SmartTVs) choke on 204 
} 
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') 
}) 

var express = require('express') 
var cors = require('cors') 
var app = express() 
var whitelist = ['http://example1.com', 'http://example2.com'] 
var corsOptions = { 
  origin: function (origin, callback) { 
    if (whitelist.indexOf(origin) !== -1) { 
      callback(null, true) 
    } else { 
      callback(new Error('Not allowed by CORS')) 
    } 
  } 
} 
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') 
}) 

app.get('/jsonp', (req, res) => {
  const callback = req.query.callback;
  const data = { message: 'Hello, this is JSONP response' };
  res.type('text/javascript');
  res.send(`${callback}(${JSON.stringify(data)})`);
});