nodejs set service proxy cross domain

With the rapid development of Internet technology, the ways of transmitting data are becoming more and more diverse. However, transferring data across domains is a problem due to various security restrictions. This article will introduce how to use Node.js to set up a service proxy across domains.

1. What is cross-domain

Cross-domain means that when the client requests resources under another domain name through Ajax, the browser will comply with the same-origin policy and find that the request is cross-domain Requests from non-original sources will be blocked. Therefore, cross-domain requests often fail due to security policies.

2. Why cross-domain requests are needed

The emergence of cross-domain requests is mainly to facilitate data interaction between various sites. For example, when we access a web application, we may need to obtain data from different sites. In this case, cross-domain requests are necessary.

3. Cross-domain solution

1. JSONP (JSON with Padding) realizes cross-domain

JSONP is a standard cross-domain solution , which dynamically creates script tags, wraps data in callback functions and returns them together.

2. CORS (Cross-Origin Resource Sharing) realizes cross-domain

The CORS specification is a cross-domain resource sharing standard developed by W3C. By setting Access on the server -Control-Allow-Origin response header to solve cross-domain issues. However, CORS is only supported in advanced browsers, and is not supported by lower version browsers.

4. Use Node.js to implement cross-domain service proxy

Cross-domain service proxy refers to sending a request to the server of the same source, and then the server proxy requests data from the target server , thereby implementing cross-domain requests. The following is sample code for using Node.js to implement service proxy cross-domain.

//导入所需的模块
const http = require('http');
const https = require('https');
const url = require('url');
const querystring = require('querystring');

//创建HTTP服务器
http.createServer(function(req,res) {
  //获取请求URL
  let aimUrl = req.url;

  //解析请求地址
  let urlObj = url.parse(aimUrl,true);

  //获取目标地址
  let targetUrl = urlObj.query.url;

  //解析参数
  let paramsObj = urlObj.query;

  //删除URL中的url参数
  delete paramsObj.url;

  //将JSON格式的querystring参数转化为querystring
  let params = querystring.stringify(paramsObj);

  //设置目标URL
  let options = {
    protocol: url.parse(targetUrl).protocol,
    hostname: url.parse(targetUrl).hostname,
    port: url.parse(targetUrl).port,
    path: url.parse(targetUrl).pathname + '?' + params,
    method: 'GET',
    headers: {
      'Content-Type': 'application/x-www-form-urlencoded'
    }
  };

  //发起请求
  let request = https.request(options, function(response) {
    //设置响应数据类型
    res.writeHead(response.statusCode, {'Content-Type': 'application/json'});

    //监听data事件
    response.on('data', function(chunk) {
      res.write(chunk);
    });

    //监听end事件
    response.on('end', function() {
      res.end();
    });
  });

  //设置请求超时时间
  request.setTimeout(3000, function() {
    res.writeHead(500, {'Content-Type': 'application/json'});
    res.write(JSON.stringify({error: 'timeout'}));
    res.end()
  });

  //监听错误事件
  request.on('error', function(error) {
    res.writeHead(500, {'Content-Type': 'application/json'});
    res.write(JSON.stringify({error: error}));
    res.end();
  });

  //设置请求方式
  request.method = req.method;

  //发起请求
  if (req.method == 'POST' || req.method == 'PUT') {
    req.on('data', (data) => {
      request.write(data);
    });
    req.on('end', () => {
      request.end();
    });
  } else {
    request.end();
  }
}).listen(8080, 'localhost');

5. Summary

This article introduces the principle of cross-domain requests and two common cross-domain solutions (JSONP and CORS), and also uses Node.js to implement service proxy cross-domain This method solves the problem of cross-domain requests by making data requests on the server side. Server-side cross-request is a safe and stable method, which can make cross-domain requests more secure and suitable for various complex scenarios.

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