How to refresh asynchronously in jquery

In web development, asynchronous refresh technology is often used to implement some special functions, such as partial refresh, real-time update, etc. The core technology to achieve asynchronous refresh is Ajax technology. As one of the most popular JavaScript libraries, jQuery encapsulates Ajax functions that are very powerful and easy to use. In this article, we'll take an in-depth look at how to implement asynchronous refresh using jQuery.

1. jQuery asynchronous refresh principle

In traditional synchronous requests, the client sends a request to the server and then waits for the server to respond. In an asynchronous request, the client does not have to wait for the server to respond after sending the request, but continues to execute subsequent code. When the server responds, relevant processing is performed based on the response results. In this way, partial refresh of the website can be achieved and unnecessary network traffic and resource waste caused by page reloading can be avoided.

jQuery's asynchronous refresh relies on Ajax technology. The principle is:

1. The client sends an asynchronous request to the server and uses the XMLHttpRequest object to create an XMLHttpRequest object for sending asynchronous requests.

2. Before sending a request, the client needs to configure the request first, including the request type, requested URL, request parameters, etc.

3. The client sends a request to the server and registers a callback function. After the server has processed the request, it returns the response result to the client. The client executes the corresponding callback function based on the response result.

4. The client performs corresponding operations based on the server response, such as updating part of the web page.

2. Implementation of jQuery asynchronous refresh

There are two main methods of asynchronous refresh in jQuery: $.ajax() and $.get() methods, where $.get() is $. A simplified version of ajax(), suitable for scenarios where only URL and data are passed in the request. The following will introduce how to use these two methods respectively.

1. Use the $.ajax() method to implement asynchronous refresh

The $.ajax() method is one of the most commonly used methods in jQuery for sending asynchronous requests. It uses Promise to make asynchronous requests easier to manage. The basic usage of the $.ajax() method is as follows:

$.ajax({

type: 'POST',  //请求类型
url: 'http://www.example.com/api',  //请求的URL地址
data: {username: '张三', password: '123456'},  //请求的参数
success: function(data){  //回调函数，处理服务器响应结果
    // 服务器响应成功后执行的代码
},
error: function(xhr, type){  //回调函数，处理服务器响应错误
    // 服务器响应失败后执行的代码
}

});

The above code is first sent using the $.ajax() method A POST request was made, the requested URL address was http://www.example.com/api, and the request parameters were {username: 'Zhang San', password: '123456'}. When the server responds successfully, jQuery will execute the success callback function and pass the response data as a parameter to the callback function. If the server responds with an error, jQuery will execute the error callback function and pass the XMLHttpRequest object and error type as parameters to the callback function.

2. Use the $.get() method to implement asynchronous refresh

The $.get() method is a simplified version of the $.ajax() method, suitable for passing only the URL and Data scenarios. The basic usage of the $.get() method is as follows:

$.get('http://www.example.com/api', {username: 'Zhang San', password: '123456'}, function(data){

// 处理服务器响应结果

})

The above code first uses the $.get() method to send a GET request to the http://www.example.com/api address, and Pass the parameters {username: 'Zhang San', password: '123456'} to the server. When the server responds successfully, jQuery will execute the callback function and pass the response result as a parameter to the function.

3. Example of jQuery implementing asynchronous refresh

Below we will use an example to specifically illustrate how to use jQuery to implement asynchronous refresh. In this example, we will use the $.get() method to get the current time from the server and update it to the specified DIV on the web page. The specific code is as follows:

HTML code:

<meta charset="UTF-8">
<title>jQuery异步刷新实例</title>

<h1>当前时间：</h1>
<div id="time"></div>

<script src="http://libs.baidu.com/jquery/2.0.0/jquery.min.js"></script>
<script src="refresh.js"></script>

JavaScript code (refresh.js):

function refreshTime () {

$.get('http://www.example.com/get_time', function(data) {
    $('#time').text(data.time);
});

}

setInterval(refreshTime, 1000);

The above code first defines a refreshTime() function, which uses the $.get() method Send a GET request to http://www.example.com/get_time and update the time field in the response result to the DIV with ID time. Then use the setInterval() method to execute the refreshTime() function every 1 second.

In this way, when a user visits the webpage, the time on the page can always be updated in real time without reloading the entire page. Such an experience will be smoother and easier for users to accept.

Summary

This article details how to use jQuery to implement asynchronous refresh technology. First, the principle of jQuery asynchronous refresh is explained, and then the two main asynchronous refresh methods are introduced: $.ajax() and $.get() methods. Finally, a specific example demonstrates how to use asynchronous refresh technology to achieve real-time updating of web pages. I hope this article can help you better master jQuery asynchronous refresh technology and improve web development efficiency.

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