How vue deployment server solves cross-domain problems

Vue.js is an excellent front-end development framework that is widely used in the development of web applications. It helps developers quickly build modern, efficient applications. However, in actual development, we may encounter cross-domain problems, especially when we deploy Vue.js applications to the server. This article details how to resolve cross-domain issues in Vue.js applications.

What is cross-domain?

To put it simply, cross-domain means requesting resources from another website in a page of one website. Cross-domain problems are mainly caused by the browser's same-origin policy. The same-origin policy is a client-side security policy that prevents web applications from obtaining private information from documents or scripts loaded from one source from another source.

Why do we need to cross domain?

In actual development, we often need to access APIs or resources of other websites across domains. For example, we may need to obtain data from different servers or call interfaces of other websites. For example, in a Vue.js application, we might need to send an AJAX request to the server to get data. If the server does not allow cross-domain requests, the data cannot be obtained and the application will not work properly.

Methods to solve cross-domain problems

1. Add CORS header information on the server side

CORS (cross-domain resource sharing) is a mechanism that Allows the browser to send cross-domain requests to the server, and allows the server to return cross-domain responses. CORS is a standard implemented by browsers so it can solve cross-domain issues for front-end applications.

The method of adding CORS header information on the server side is very simple, just add some specific header information to the returned HTTP response. The details are as follows:

Access-Control-Allow-Origin: *
Access-Control-Allow-Methods: GET, POST, PUT, DELETE, OPTIONS
Access-Control-Allow-Headers: Content-Type, Authorization

The meaning of the above header information is as follows:

• Access-Control-Allow-Origin: Specify the allowed domain name. * indicates that all domain names are allowed, or one or more domain names can be specified.
• Access-Control-Allow-Methods: Specify allowed HTTP methods.
• Access-Control-Allow-Headers: Specify allowed HTTP header information.

The disadvantage of this method is that header information needs to be added on the server side. If the application needs to access multiple different servers or APIs, it needs to be configured on each server.

2. Using JSONP

JSONP is a cross-domain solution that takes advantage of the browser's ability to access cross-domain <script> tags support. The principle of JSONP is to convert cross-domain requests into a <script> tag. The src attribute of this tag points to the server program that solves cross-domain problems. The server program returns a piece of JavaScript code. , this code passes the returned data as a parameter to a function on the front-end page.

The method of using JSONP in Vue.js is very simple. Just introduce a JSONP library and use the $jsonp() method to send a JSONP request. The details are as follows:

import jsonp from 'jsonp';

jsonp('https://api.example.com/data', (err, res) => {
   if (err) {
      console.error(err);
   } else {
      console.log(res);
   }
});

The disadvantage of this method is that JSONP only supports GET requests and can only return data in JSON format.

3. Use reverse proxy

Reverse proxy is a server-side method of resolving cross-domain requests. It takes advantage of the interconnection and communication between servers, uses the server-side program as a proxy, and converts the requests in the front-end page into the requests of the back-end program, thus avoiding the same-origin policy restrictions on the browser side.

There are many ways to implement reverse proxy. You can use the reverse proxy module of web servers such as Apache and Nginx, or you can use the express framework in Node.js to implement the reverse proxy function.

The method of using reverse proxy in Vue.js is as follows:

Add the following code in the config/index.js file:

module.exports = {
  dev: {
    // ...
    proxyTable: {
      '/api': {
          target: 'http://example.com',
          changeOrigin: true,
          pathRewrite: {
              '^/api': ''
          }
      }
    }
  }
};

The above code indicates that all requests starting with /api will be forwarded to http://example.com, and the Origin field will be added to the request header. Send the request to the target server. This approach requires debugging and testing during the development phase.

In a production environment, we need to configure the reverse proxy into the server. Just use the reverse proxy module of a web server such as Nginx or Apache.

Summary

When Vue.js applications are deployed to the server, cross-domain is a common problem. This article describes three ways to solve cross-domain issues: adding CORS headers on the server side, using JSONP, and using a reverse proxy. In actual development, appropriate solutions need to be selected according to different needs and scenarios.

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