Nodejs implements cross-domain

Cross-domain means that documents or scripts in one domain try to request resources in another domain. In this case, cross-domain problems will occur because the browser has a same-origin policy. This policy Strive to ensure the security of web applications to the greatest extent possible. That is, client scripts in different domains cannot read or write each other's document content without explicit authorization.

Node.js is a popular server-side JavaScript runtime environment that makes it easy to create web applications. In Node.js, we can use multiple methods to handle cross-domain requests. The following are some common cross-domain processing methods:

1. Use CORS

CORS is the abbreviation of "Cross-domain Resource Sharing". It is a standardized cross-domain solution that allows servers to Send authorization information to the client so that the client can access resources in other domains. In Node.js, cross-domain requests can be achieved by using CORS.

It is very simple to use CORS to solve cross-domain problems in Node.js. You only need to install and use the cors module. The sample code is as follows:

const express = require('express');
const cors = require('cors');
const app = express();
 
app.use(cors());
 
app.get('/api/data', function (req, res) {
  // 处理请求
});
 
app.listen(3000, function () {
  console.log('Server listening on port 3000');
});

2. Use JSONP

JSONP is a very old technology used to solve cross-domain problems. It takes advantage of the cross-domain feature of the src attribute in HTML tags and indirectly obtains other domains by dynamically generating a script tag and setting its src attribute. data below. In Node.js, cross-domain requests can be achieved by using JSONP. The sample code is as follows:

const express = require('express');
const app = express();
 
app.get('/api/data', function (req, res) {
  const callback = req.query.callback;
  // 处理请求
  res.send(callback + '(' + JSON.stringify(data) + ');');
});
 
app.listen(3000, function () {
  console.log('Server listening on port 3000');
});

3. Using a proxy server

The proxy server is a way to transfer the client's request to the server Servers forwarded to other servers, by using proxy servers, can forward client requests to resources in other domains on the server side, thereby achieving cross-domain purposes. In Node.js, you can use http-proxy-middleware to build a proxy server. The sample code is as follows:

const express = require('express');
const { createProxyMiddleware } = require('http-proxy-middleware');
const app = express();
 
app.use('/api', createProxyMiddleware({
  target: 'http://example.com',
  changeOrigin: true,
}));
 
app.listen(3000, function () {
  console.log('Server listening on port 3000');
});

Summary

There are many ways to implement cross-domain in Node.js , where using CORS is a more convenient and standardized solution, while using JSONP and a proxy server is a less used but still feasible solution. Which solution to use can be chosen based on specific needs and scenarios, but it should be noted that cross-domain operations may affect the security of web applications, so you need to operate with caution.

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