Test Code Across Multiple Platforms

It will be clear from the content of this book that the various browsers behave differently in their implementation of JavaScript. The major difference in the generation of XMLHTTPRequest object instances between Microsoft and non-Microsoft browsers is a fundamental example, but there is a host of minor differences, too.

The DOM, in particular, is handled rather differently, not only between browsers but also between different versions of the same browser. CSS implementation is another area where minor differences still proliferate.

Although it has always been important to test new applications on various browsers, this is perhaps more important than ever when faced with the added complexity of Ajax applications.

Hopefully browsers will continue to become more standards-compliant, but until then test applications on as many different platforms and with as many different browsers as possible.