Ví dụ, bạn có thể sử dụng quá trình chuyển đổi CSS để cho biết rằng một số phần của ứng dụng của bạn là chờ đợi cho một yêu cầu HTTP đó là xử lý trên máy chủ. CSS thao tác rất nhiều con số trong định nghĩa rộng hơn của thuật ngữ AJAX trong các hình ảnh | Showing Processing Status error Could not verify your login information. Our client-side code parses this result and either redirects to the main application page or displays the error message for the user. Also note that we set Content-Type to text plain so XMLHttpRequest won t expect the response to contain valid XML. Of course this is a really basic example. You could certainly expand it to return different error messages or codes or to direct different classes of users to different parts of the application for example logging administrative users into an admin console . You could also choose a different separator character. Sometimes your data will contain commas so using a comma as a separator may not be a good idea. The pipe character is another popular choice. The CSV format is simple yet flexible enough to deal with a wide range of uses any case in which you have a limited number of data fields and you control the code on both the back end and the front. XML is better suited to more complicated types of data and situations in which your application has to communicate with other applications. Showing Processing Status While our fake processing page is pretending to authenticate the submitted data users will be staring at the login screen wondering what the heck is going on. This is where status notification again comes to the fore. It s vital to let users know what s going on with an application but it s particularly important in the case of an AJAX app as users have to sit and wait for processes on the server to finish. If the application is busy performing some task it should look busy to the user. On this login page we ll use an animation effect to indicate that the application is processing the user s request but we ll take a slightly different approach to the one we used last time. Rather than creating a sense of movement by changing the animation s opacity we ll use a line of dots similar to an ellipsis . animating them a bit like a line of Christmas .
