jquery cross domain http request data

jquery is a popular JavaScript library used to simplify DOM operations, event processing, animation effects, etc. The most common application is to request back-end data through Ajax to achieve a page refresh-free experience. However, in some cases, we need to obtain data from multiple different domain names, in which case cross-domain requests are required. This article will introduce how to use jquery to perform cross-domain http request data.

1. What is a cross-domain request?

On the browser side, due to the restrictions of the browser's same-origin policy, it is not allowed to access data under another domain name from a page in one domain name, that is, Same-Origin Policy. Homology means that the protocol, domain name, and port number must be exactly the same. For example, https://www.example.com and https://example.com have different origins, and http://www.example.com and http://www.example.org have different origins.

Cross-Origin Request refers to the process of requesting data from one source (domain name, protocol, port number) to another source. In order to implement cross-domain requests, the browser needs to complete a series of security verifications to ensure that the requested data is allowed.

2. Cross-domain request methods

Currently, the more popular cross-domain request methods are as follows:

1. JSONP

JSONP is a method to achieve cross-domain communication between different domains by adding the 3f1c4e4b6b16bbbd69b2ee476dc4f83a tag and using the browser to allow cross-domain access to JS files. JSONP can use the src attribute of the 3f1c4e4b6b16bbbd69b2ee476dc4f83a tag to make HTTP requests to other domain names, and the returned data includes code to execute a callback function, thereby realizing a cross-domain data request and callback mechanism.

2. CORS

CORS is a standard cross-origin resource sharing technology that allows the server to respond to web page requests from other sources through new HTTP headers. CORS requires browser and server support. As long as the server identifies that the response can be accessed by other domains, the browser will allow this cross-domain request.

3. Proxy

The proxy method refers to deploying a proxy server under the same domain name, then letting the proxy server request data from other domain names, and finally returning the request results. Solutions for the front end. The premise that this method is feasible is that there are no cross-domain restrictions on the interfaces being accessed. It is suitable for situations where the JSONP protocol is not supported and CORS cannot meet cross-domain requirements.

4. PostMessage

PostMessage is an API for cross-document communication between windows. It provides a way of cross-source communication, allowing one document to send messages to another document. Send a message regardless of whether the two documents have the same origin.

5. WebSocket

WebSocket is a new protocol for HTML5. It is a two-way communication protocol based on the TCP protocol and can achieve cross-domain communication. It is different from the HTTP protocol. WebSocket will create a TCP connection for data transmission, and a protocol upgrade is required when establishing the connection.

The above methods each have their own advantages and disadvantages. Choose the appropriate cross-domain request method according to the specific scenario.

3. Use jquery for cross-domain requests

Using jquery for cross-domain requests mainly requires the use of the ajax method in jquery. This method supports asynchronous requests and synchronous requests, as well as Support for two common request methods, GET and POST. The specific usage is as follows:

1. JsonP request

Jsonp data request needs to specify that the data format returned by the server is jsonp format and contains a parameter named callback with a value of The name of the callback function, and the callback function name is implemented through the callback callback parameter of the src parameter of the jsonp script tag.

$.ajax({

url: 'http://example.com/jsonp',
type: 'GET',
dataType: 'jsonp', //指定数据类型为jsonp
jsonp: 'callback', //指定回调函数名称
success: function(res) {
    console.log(res);
}

});

2. Cors request

Cors request is made by adding Access in the header -Control-Allow-Origin field is implemented. In jquery, when sending a cross-domain request through the ajax method, you can implement the cross-domain request by setting the xhrFields parameter. Among them, the withCredentials parameter is used to control whether the browser carries cookie information.

$.ajax({

url: 'http://example.com/cors',
type: 'GET',
xhrFields: {
    withCredentials: true //允许携带cookie信息
},
success: function(res) {
    console.log(res);
}

});

4. Summary

Cross-domain requests are a very common requirement in front-end development. This article This article introduces common cross-domain request methods and how to use jquery to perform cross-domain http request data. Different cross-domain request methods have their own advantages and disadvantages. Choose the appropriate method according to specific needs. When implementing cross-domain requests, you need to pay attention to security issues to avoid malicious attacks.

The above is the detailed content of jquery cross domain http request data. For more information, please follow other related articles on the PHP Chinese website!