What causes an Ajax request to timeout?

Under what circumstances will an Ajax request expire?

With the development of Web applications, Ajax (Asynchronous JavaScript and XML) technology has become an indispensable part of Web development. Through Ajax, we can obtain data from the server and dynamically update the content of the web page without refreshing the entire page. However, when using Ajax to send requests, sometimes you encounter request expiration. So, under what circumstances will an Ajax request expire? Below I will analyze it from multiple perspectives and provide corresponding code examples.

1. The server response time exceeds the set timeout period
   When using Ajax to send a request, we can set the timeout period in the request parameters. If the server response time exceeds the set timeout, the request will be considered expired. The following is a sample code:

$.ajax({
  url: 'example.php',
  timeout: 3000, // 设置超时时间为3秒
  success: function(data) {
    // 请求成功的处理逻辑
  },
  error: function() {
    // 请求失败的处理逻辑
  }
});

2. The number of interface requests exceeds the server limit
   Some backend interfaces may limit the request frequency of each client, such as only allowing Send 10 requests. If we send too many requests in the page and exceed the server's limit, the request will be considered expired by the server. The following is a sample code:

var count = 0;

function sendRequest() {
  if (count >= 10) {
    // 请求次数超过限制
    return;
  }

  $.ajax({
    url: 'example.php',
    success: function(data) {
      count++;
      // 请求成功的处理逻辑
    },
    error: function() {
      // 请求失败的处理逻辑
    }
  });
}

3. Front-end network problems cause request timeouts
   In addition to the server response time being too long and the number of requests exceeding the limit, front-end network problems may also cause Ajax requests Expired. For example, if the client's network is unstable or network latency is high, the request may time out. The following is a sample code:

$.ajax({
  url: 'example.php',
  timeout: 3000, // 设置超时时间为3秒
  success: function(data) {
    // 请求成功的处理逻辑
  },
  error: function() {
    // 请求失败的处理逻辑
  }
});

To sum up, Ajax request expiration may be caused by a variety of factors, including server response time is too long, the number of interface requests exceeds the limit, and front-end network problems, etc. . In actual development, we should reasonably set the timeout and request limit according to the specific situation, and handle network problems, so as to effectively avoid the occurrence of Ajax request expiration problems.

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