Ajax Basics Tutorial (1)-ajax Introduction 1.4 Usability issues

All of the above are the expectations of the user, and in addition, usability cannot be mentioned. The AJAX approach is quite new, and there is not much mature best practice. However, the standard web design principles are still applicable. Over time, as more and more people start experimenting with this approach, they will find out what limitations might exist and establish appropriate guidelines. In other words, you should let the user guide you. Depending on how Ajax is used in your application, you may change some parts of the page dynamically, and users who are accustomed to refreshing the entire browser may not notice any change compared to the previous one. This problem leads to some new features, such as the popular yellow fade technology in 37signals (Yellow Fade technique,yft), which has been used in the Ajax signboard application Basecamp.

Basically, yft refers to "take the changed part of the page and place it in yellow." If your application doesn't have a lot of yellow, users are likely to notice the change. After a period of time, let the yellow fade gradually until the original background color is restored. Of course, you can also choose the other colors you like, as long as you can draw the user's attention to the changing parts.

YTF may not apply to your application, you can also choose to use a less publicized but still useful way to remind users. Gmail displays a flashing red "Loading" load mark in the upper-right corner, reminding users that they are getting the data (see Figure 1-7).

Figure 1-7 Gmail's "Loading" sign

Whether you want to use YFT or other similar techniques actually depends on your users. The easiest way to do this is to have a group of user representatives test. You can use a text questionnaire or a web-based prototyping application, which depends on where you are in the design process. But no matter how you test, you should get some user feedback before you can really use Ajax to complete a complex design.

And do it from a small place. When you start using AJAX, you should not create an adjustable column dynamic portal right away, but instead try to process client-side validation and move on to the server. After you know it, you can try more dynamic use, such as filling out a drop-down list, or setting some default text.

No matter how you apply Ajax, remember not to do weird things. We know that this is not an academic proposal. However, there are no strict rules in this regard. First listen to what the user says, before you deploy, be sure to test, and remember that if it's too weird, users will quickly click the "Skip this page" link to skip over your carefully designed sections.

You know, there are a few common mistakes in using AJAX. We've discussed how to provide visual cues to users when they change, and not only that, but Ajax will also change the standard Web methods in other ways. First, unlike the IFRAME and hidden frames, making requests through XHR does not modify the browser's history stack. In many cases this is not a problem (you might click the back arrow, just to see if nothing has changed, but how many times does it have to be done?) , but if your users really want to use the back button, there's a problem.

Second, unlike other browser-based methods, Ajax does not modify the links displayed in the address bar, which means you can't easily bookmark a page or send a link to a friend. For many applications, this may not be the case, but if your site is dedicated to providing traffic routes and the like, you should provide a solution to this problem.

It is important to use Ajax not to overdo it. Remember, JavaScript runs on the client's browser, and if there are thousands of lines of JavaScript code, it may make the user feel too slow. If the script is not written properly, it will quickly lose control, especially if the traffic is increasing.

Ajax allows you to complete the operation asynchronously, the biggest advantage of which is also its most prominent disadvantage. We've always told users that Web apps are done in a request/response pattern, and the user has accepted the idea. But with Ajax, there is no longer a limit. We can only modify part of the page, and if users don't think about it, they are likely to get confused. So, you have to be careful to let the user understand this, do not assume that they know. Remember, as long as you have questions, you should ask the user representative to test!

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