通过在后台与服务器进行少量数据交换，Ajax 可以使网页实现异步更新。这意味着可以在不重新加载整个网页的情况下，对网页的某部分进行更新(Ajax enables asynchronous updating of web pages by exchanging a small amount of data between the server and the background. This means that a part of the web page can be updated without reloading the entire web page)