What does jquery's callback function mean?

The jQuery callback function refers to executing a custom function provided by the user when a jQuery action, such as an AJAX request, an animation or an event is completed. The callback function can be registered when these actions are not completed. It is called after the operation is completed and can accept parameters passed in from the outside, which can enhance the scalability and maintainability of the code.

Operating system for this tutorial: Windows 10 system, jQuery3.6.0 version, Dell G3 computer.

jQuery callback function refers to executing a custom function provided by the user after a jQuery action (such as an AJAX request, an animation, or an event) is completed. The callback function can be registered when these actions are not completed, be called after the operation is completed, and can accept parameters passed in from the outside.

The following is an example of how to use the jQuery callback function:

```
// 通过AJAX加载数据
$.ajax({
    url: "example.php",
    success: function(result) {
        // 在成功响应时调用的回调函数
        alert("数据加载完成！");
    },
    error: function(xhr, status, errorMsg) {
        // 在响应失败时调用的回调函数
        alert("请求失败：" + errorMsg);
    }
});
```

In the above code, when the AJAX request is successful, the code in the `success` callback function will be executed, and when the request fails The `error` callback function will be executed.

The main benefit of using callback functions is to enhance the scalability and maintainability of the code. By separating functions from specific operations, we can more easily modify the code logic, add new functions, and enhance the flexibility of the program while keeping the original code unchanged.

In addition, due to the event and asynchronous operation characteristics in JavaScript, callback functions are also a very widespread programming pattern. Its use is not limited to the jQuery library, but also applies to other JavaScript frameworks and the language itself.

The above is a brief introduction and usage examples of jQuery callback functions.

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