Vue deploys online to solve cross-domain problems

Vue.js is a popular JavaScript framework for building single page applications (SPA). When developing Vue applications, you may encounter cross-domain issues. Cross-domain issues often prevent browsers from loading resources from different origins. In fact, when deploying Vue applications, cross-domain issues can become bottlenecks in many aspects. This article will introduce Vue.js deployment while focusing on how to solve cross-domain problems.

What is cross-domain?

In a browser, when a script is executed in the document tree of a Web page, the executed script can access any part of the document tree. However, cross-domain issues arise when trying to access resources from different sources.

Source

The source refers to the server or client in the network, which can be an IP address, domain name or port number. The browser determines whether two URLs are the same by comparing the components of the source to determine whether they are cross-domain.

For example, suppose we have the following URLs:

http://www.example.com/page1
https://www.example.com/page2
http://www.example.com:8080/page3

Each of them contains three components: protocol, host, and port number. In this example, the first and third URLs have the same protocol and host, but their port numbers are different. Due to the different port numbers, these URLs are considered different sources.

Cross-domain

When a JavaScript script attempts to access resources from other sources, the browser will block the execution of the script according to the same origin policy. Browsers think this will prevent malicious scripts from stealing data.

For example, if the JavaScript code of a component in a Vue.js application attempts to access an API from another source, the application will make a cross-origin request to the browser. If cross-domain issues are not resolved, browsers will prevent applications from loading required resources from other sources.

Solving cross-domain problems

To solve the cross-domain problems of Vue.js applications, we need to consider multiple aspects: back-end API cross-domain, front-end packaged static resources cross-domain, etc., we will discuss them separately. look.

Backend API cross-domain

In a Vue.js application, the API needs to interact with the front-end application. If these APIs are in different domains, cross-domain needs to be done. You can solve this problem through the following methods:

1. Through the Access-Control-Allow-Origin HTTP header

By setting the Access-Control-Allow-Origin header on the API server side, The browser can solve cross-domain problems by specifying the address of a trusted reverse proxy server.

The Access-Control-Allow-Origin HTTP header identifies which domain names are trusted by the server. If this header contains the address requested from the client, the API server will allow the request to pass.

Access-Control-Allow-Origin: http://your-domain.com/

To allow all domain names to access the API, you can use wildcards:

Access-Control-Allow-Origin: *

This solution is very simple, but it is very restrictive and not suitable for most applications.

2. Add a reverse proxy server

In order to better control which requests can pass through the reverse proxy, you can use a reverse proxy server, such as Nginx. A reverse proxy server is used to obtain data from a remote server (such as an API server) and return it to the client.

When using a reverse proxy, the API server will not be exposed to the Internet. Instead, the client will send a request to the reverse proxy and get data from it. A reverse proxy server controls which requests pass through the request pipeline.

For example, for a certain API of a Vue.js application, you can set the following Nginx server configuration:

location /api/ {
   proxy_pass http://your-api-server.com/;
   add_header 'Access-Control-Allow-Origin' 'http://your-domain.com/';
}

The above settings specify all paths to /api/* The request will be forwarded to the API server. When a request is sent from a user with the domain name your-domain.com, the reverse proxy server will allow the request to pass through. Only requests from this domain will be allowed. Other domain names will be rejected.

Packaging static resources across domains after the front-end application is deployed

The Vue.js application will be packaged as a static file in the production environment and will be deployed on the server where the application is located. If your front-end application and API are deployed on different servers, when encountering this situation, we need to do the following:

1. Add publicPath

packaging in the Vue configuration file Good front-end static code, if publicPath is not set, will reference related resources through relative paths. The relative path import method will use './', '../', etc. to represent the path identifiers of the imported resources, and the paths represented by these identifiers are only relative to the code files.

In the packaged static resources, you will find that the resource paths are accessed as relative paths. If you copy the packaged code directly to other servers for access, you will find that access problems will occur.

In order to solve this problem, you need to add a publicPath when packaging static files and change all paths to absolute paths.

Before deployment, open the vue.config.js file and add a publicPath address. For example:

module.exports = {
    publicPath: 'http://cdn.example.com/vue-app'
}

This configuration tells Webpack to configure publicPath as a custom address when generating static resources, so that when accessing other domain names, the code can be loaded directly through CDN resources, solving the problem of cross-domain resource requests. .

2. Set CORS rules

When both static resources and API resources are under the CDN domain name, you need to set CORS rules instead of using Nginx reverse proxy, because Nginx will generally There is a layer of CDN acceleration.

Set cross-domain CORS rules on the CDN console, turn on the Access-Control-Allow-Origin header, allow front-end code to access static resources, and solve the problem of cross-domain resource access.

Conclusion

When developing Vue.js applications, solving cross-domain issues is an important step. This article details how to solve cross-domain problems in Vue.js. We need different cross-domain solutions for different scenarios. By understanding and mastering cross-domain issues, we can effectively improve the performance and reliability of Vue.js applications.

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