Cross-domain solutions

1.jsonp

router.get('/', function(req, res, next) {
  let _callback = req.query.callback
  {limitNum the let, pageCode} = req.query; // Get paging data submitted by the user 
  limitNum limitNum * = 10. 1 || 
  pageCode = pageCode *. 1 || 0 
  sql.paging (the User, {}, {the _id: 0}, limitNum, pageCode) .then (Data => {
     var obj = {
      code: '200',
      message: 'success',
      date:
    }
    IF (_callback) {
       // This two-step transmission is provided NODE.JS transmission JSONP necessary 
      res.type ( 'text / JavaScript' );
      res.send(_callback + '(' + JSON.stringify(obj) + ')');
    } else {
      res.json(obj)
    }
  })
});

// distal 
$ .ajax ({
  url: 'http://localhost:3000/users',
  dataType: 'jsonp',  // ******************************
  success: function (data) {
    console.log(data)
  }
})

2.cors

// app.js add the following code 
var allowCrossDomain = function (REQ, RES, Next) {
  res.header ( 'Access-Control-the Allow-Origin', '*'); // custom middleware, setting desired cross-domain response header. 
  next ();
}; 
app.use (allowCrossDomain) // // use cross-domain Middleware

3. Reverse Proxy

Client Access server encountered cross-domain problem, but there is no cross-domain issues before the server and the server.

Request their own server, your own server to ask for someone else's server.

Forward Proxy "proxy object is a client," reverse proxy "proxy object is a server.