How jsonp solves cross-domain problems

JSONP is a technology that enables cross-domain requests by dynamically creating tags. The steps are as follows: 1. Create a callback function in the client page, which is used to process the data returned from the server; 2. Dynamically create a tag, set its src attribute to the URL of the target server, and A parameter is passed in the URL, which is the name of the callback function; 3. After the server receives the request, it wraps the data in the callback function in the returned data and returns it to the client, etc.

JSONP (JSON with Padding) is a technology used to solve cross-domain requests, which allows web pages in different domains to Perform cross-domain data access. Before introducing how JSONP solves cross-domain problems, we first need to understand the nature and causes of cross-domain problems.

Cross-domain problems are caused by the browser’s Same-Origin Policy. The Same Origin Policy is a security mechanism that requires browsers to restrict how documents or scripts loaded from one source interact with resources from another source. The same-origin policy requires that scripts in web pages can only access resources from the same source and cannot directly access resources in other domains. This restriction is to protect user privacy and security and prevent malicious websites from stealing user information or conducting malicious attacks.

JSONP is a technology that enables cross-domain requests by dynamically creating tags. Its basic principle is to realize cross-domain data transmission by taking advantage of the fact that the tag has no cross-domain restrictions. How JSONP solves cross-domain problems will be discussed in detail below.

1. The working principle of JSONP:

The working principle of JSONP It's very simple, it dynamically creates a tag, requests data from the server, and passes the name of a callback function in the request. After receiving the request, the server packages the data in this callback function and returns it to the client. After the client receives the data, it can process the returned data through the callback function. This enables cross-domain data access on web pages in different domains. 2. Steps to implement JSONP request:

The following are the basic steps to implement JSONP request:

a. Create a callback function in the client page, which is used to process the data returned from the server.

b. Dynamically create a tag, set its src attribute to the URL of the target server, and pass a parameter in the URL, which is the callback function. name.

c. After the server receives the request, it wraps the data in the callback function in the returned data and returns it to the client.

d. After the client receives the returned data, it can process the data through the pre-defined callback function.

3. Advantages and disadvantages of JSONP:

As a solution for cross-domain requests, JSONP has Some pros and cons. The first is its advantage:

Simple and easy to use : The implementation of JSONP is very simple, you only need to dynamically create the tag, And set the callback function.

Good compatibility : JSONP has good compatibility, almost all browsers support JSONP.

Cross-domain capability : JSONP can well solve the problem of cross-domain requests, allowing web pages in different domains to interact with data.

However, JSONP also has some shortcomings :

Security issues : JSONP has security risks because it implements cross-domain requests by dynamically creating tags, so there is a risk of malicious script injection.

Only supports GET requests : JSONP only supports GET requests and cannot support other types of requests such as POST.

Depends on server support : To use JSONP, the server needs to specifically support returning data in JSONP format. If the server does not support it, it cannot be used. JSONP for cross-domain requests.

4. JSONP usage scenarios:

JSONP is suitable for some simple cross-domain request scenarios , such as obtaining data from third-party websites, calling third-party APIs, etc. Due to some security and functional limitations of JSONP, other cross-domain solutions may need to be considered for some complex cross-domain request scenarios.

In general, JSONP is a simple and effective solution for cross-domain requests, which uses the tag. Cross-domain capabilities enable data interaction between different domains. However, with the development of the Internet and the improvement of security requirements, JSONP may be limited in some scenarios. Therefore, in practical applications, appropriate cross-domain solutions need to be selected based on specific business needs and security considerations.