1.5. Gmail Brings XMLHttpRequest into the Mainstream
Figure 1-4. Gmail Web mail interface
Figure 1-5. Gmail's loading indicator
There are still some minor issues with the Gmail application, and many AJAX applications will run into these issues. For instance, the browser's bookmark feature becomes useless because the URL doesn't change when content is updated, and the URL is the only identifier that the browser stores. In addition, the user interface looks similar to a native application, but it behaves differently, which can be a problem for some users because the application will fail to meet their expectations. Still, the application does attempt to alleviate this problem by giving feedback messages that tell users that an action is complete. The messages include notices that labels have been added to emails (see Figure 1-6).
Figure 1-6. Gmail provides feedback for completed actions
Because Gmail was one of the first mainstream AJAX-powered applications, it set a baseline for what users could expect. For instance, its replacement of standard browser functions, such as refresh, with links inside the application is a technique that has been copied by many other applications. This has helped increase the quality of many AJAX applications because Gmail does a good job of providing a consistent and highly usable experience.