uniapp settings spanning access

Uniapp is a cross-platform development framework that allows developers to use a set of code to write applications that run on multiple platforms at the same time. When developing with Uniapp, a common question is how to set up cross-domain access. This article will introduce the cross-domain access setting method and precautions of Uniapp.

1. What is cross-domain access

Cross-domain access refers to the issue of security restrictions when the client requests non-original resources on the server. The so-called non-original request means that at least one of the three elements of protocol, domain name, and port number is different from the current request. For example, using ajax in a web page to send requests to servers under different domain names is considered cross-domain access.

2. Uniapp’s cross-domain access setting method

Uniapp can use the uni.request method to make network requests. This method supports setting parameters such as header, method, dataType, etc., and can be used to implement cross-domain access. The following is a sample code that allows cross-domain access:

uni.request({
  url: 'http://www.example.com/api',
  method: 'GET',
  dataType: 'json',
  header: {
    'Access-Control-Allow-Origin': '*', // 允许所有源访问
    'Access-Control-Allow-Methods': 'GET,POST,OPTIONS', // 允许的请求方法
    'Access-Control-Allow-Headers': 'X-Requested-With,Content-Type', // 允许的请求头
  },
  success: function (res) {
    console.log(res.data);
  },
  fail: function (res) {
    console.log(res.errMsg);
  }
});

The Access-Control-Allow-Origin parameter in the above code specifies the allowed sources. The wildcard character '*' is used here to indicate that access from all sources is allowed. The Access-Control-Allow-Methods parameter specifies the allowed request methods. Three methods, GET, POST, and OPTIONS, are allowed here. The Access-Control-Allow-Headers parameter specifies the allowed request headers. Two request headers, X-Requested-With and Content-Type, are allowed here.

In addition to setting cross-domain access parameters in the request header, you can also set the response header on the server side. For example, the following code can be used to set the response header in PHP:

header("Access-Control-Allow-Origin: *");
header("Access-Control-Allow-Methods: GET,POST,OPTIONS");
header("Access-Control-Allow-Headers: X-Requested-With,Content-Type");

Similarly, similar code can be used to set the response header in other back-end languages ​​to achieve cross-domain access.

3. Precautions for cross-domain access

1. Security considerations: There are security risks in allowing access from all sources. It is recommended to use specific domain names for settings in the production environment.
2. Pre-request problem: When using different protocols, domain names, and port numbers, cross-domain access pre-requests will occur. Pre-requests are generally sent automatically by the browser, and the actual request is sent after the server returns corresponding response headers such as Access-Control-Allow-Origin. Since pre-requests generally take up more resources, you need to avoid or reduce pre-requests as much as possible during development.
3. JSONP problem: JSONP is a cross-domain access method, but its security is not high. When using JSONP, you need to pay attention to avoid XSS attacks, such as filtering the returned data and other measures.

4. Conclusion

Cross-domain access is one of the common problems in web development. You also need to pay attention when using Uniapp for development. This article introduces the Uniapp cross-domain access setting method and precautions, hoping to help readers solve related problems.

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