Datasheet

You should be getting a feel by now that each of these reasons is qualified — the use of Ajax can hinder

usability, not aid it; however, if development is considered, if you take steps to address the problems

with Back buttons and bookmarks, then there’s no reason why Ajax techniques shouldn’t be used. It

does raise a question, though.

If Garrett’s seminal article was so flawed, then why is it so popular? This might be because it articulated

what a lot of people were thinking and doing already, but didn’t have a name for. It didn’t matter that

there were some inaccuracies about the methods of execution. It completely struck a chord with devel-

opers. You could liken it to some of the early Beatles recordings that weren’t the best played, but they’re

rightfully remembered affectionately because the tunes always shone through. Even developers who

had issues with the article agreed that it described a sensible approach to creating web applications and

that it revisited old techniques that had been either ignored or forgotten.

Who Can/Can’t Use Ajax?

It might go without saying that not everyone will be able to use Ajax. You should always be aware of

any portion of your web site that might exclude some users by its use of a particular technology, and

you should consider how to address that portion of the target audience.

Here are some of the main considerations:

❑ Users of reasonably modern versions of the main browsers (IE 4+, Mozilla Firefox/Netscape 7+,

Safari, and Opera 5+) will find they can use Ajax applications just fine. Users of older browsers

won’t be able to.

❑ People who have scripting languages disabled won’t be able to use Ajax (or indeed JavaScript

applications). Before you scoff, just remember that after some of the recent vulnerabilities in

both IE and Microsoft Outlook, the initial advice from Microsoft was to disable active scripting

until a patch was in place to fix the vulnerability.

❑ People browse applications offline. Again, it might almost seem a prehistoric way of using the

Web, but it is, in fact, a very modern way, too. Mobile communications charge a lot more for

bandwidth and offer a lot less throughput, so it’s very common to log in, download, and log

out. Sites such as AvantGo allow you to browse a series of web pages offline that you have sub-

scribed to. If Ajax were included in these pages, it would break them.

Once again, be aware of who your target audience is and what their needs are.

Create Your Own Example

You shouldn’t come away from this chapter feeling “so why bother using Ajax?” This hasn’t been the

point. There is a time and a place for using Ajax correctly. Consider it like a fast car. Sure, it’s capable of

doing 0–60 mph in 7 seconds and can reach top speeds of 150 mph. But in town or on the freeway is not

the place to demonstrate those capabilities. You will incur the wrath of the rest of the populace, not to

mention the police. The same goes for Ajax. If you use it at every available opportunity, you won’t find

quite as many visitors to your site as you perhaps envisioned.

Chapter 1: Introducing Ajax

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