Exposing Ajax exceptions and a list of ways to resolve errors

Ajax anomaly revealed, how to deal with various errors requires specific code examples

In 2019, front-end development has become an important position that cannot be ignored in the Internet industry. As one of the most commonly used technologies in front-end development, Ajax can realize asynchronous page loading and data interaction, and its importance is self-evident. However, various errors and exceptions are often encountered when using Ajax technology. How to deal with these errors is a problem that every front-end developer must face.

1. Network Error

When using Ajax to send requests, the most common error is network error. Network errors may be caused by various reasons, such as server downtime, network disconnection, DNS resolution errors, etc. In order to deal with network errors, we can use try-catch statements to capture exceptions and give users friendly prompts.

$.ajax({
    url: 'http://www.example.com/api',
    success: function(data) {
        // 处理返回的数据
    },
    error: function(xhr, status, error) {
        console.log('网络错误：' + error);
        // 友好提示用户网络错误
    }
});

2. Server returns error code

When the status code returned by the server is not 200, we need to process it according to the specific error code. Common status codes include 404 (resource not found), 500 (server internal error), etc. We can perform corresponding processing according to the status code in the error callback function.

$.ajax({
    url: 'http://www.example.com/api',
    success: function(data) {
        // 处理返回的数据
    },
    error: function(xhr, status, error) {
        console.log('错误码：' + xhr.status);
        // 根据具体的状态码进行处理
        if (xhr.status === 404) {
            // 资源未找到，提示用户重试或其他操作
        } else if (xhr.status === 500) {
            // 服务器内部错误，提示用户稍后再试
        }
    }
});

3. Timeout error

Sometimes due to network reasons or unstable server performance, the request we send may not respond for a long time, causing a timeout error. In order to avoid users waiting for a long time, you can use the timeout parameter to set the timeout and perform corresponding processing after the timeout.

$.ajax({
    url: 'http://www.example.com/api',
    timeout: 5000, // 设置超时时间为5秒
    success: function(data) {
        // 处理返回的数据
    },
    error: function(xhr, status, error) {
        console.log('超时错误：' + error);
        // 友好提示用户请求超时
    }
});

4. Cross-domain errors

Due to the browser's same-origin policy restrictions, you may encounter cross-domain errors when using Ajax requests. In order to solve this problem, we can set the CORS (Cross-Origin Resource Sharing) policy on the server side, or use other technologies such as JSONP. Here is an example of setting the CORS policy:

// 服务器端设置CORS
Access-Control-Allow-Origin: *
Access-Control-Allow-Methods: GET, POST, OPTIONS
Access-Control-Allow-Headers: Content-Type

$.ajax({
    url: 'http://www.example.com/api',
    success: function(data) {
        // 处理返回的数据
    },
    error: function(xhr, status, error) {
        console.log('跨域错误：' + error);
        // 友好提示用户跨域错误
    }
});

The above are several common Ajax exceptions and error handling methods. Of course, there are other special errors and exceptions that need to be handled according to specific circumstances. In the actual development process, we can flexibly use these processing methods according to our own needs and project conditions to improve user experience and page performance.

Through the introduction of this article, I believe that readers have a deeper understanding of Ajax exceptions and have mastered some error handling skills. In future development work, we need to continue to learn and summarize, constantly improve our technical level, and become an excellent front-end developer.

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