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Browser and OperatingSystem Detection

Browser and Operating

System Detection

A big part of Web programming is identifying target browsers and operating systems. Whether

you are building a simple Web site or a complex Web application, this important information must

be determined before any work begins. Because browsers support different levels of HTML and

JavaScript, often differing across operating systems, you can save time and money by knowing

your targets. This ensures that you won’t include features that aren’t available to your users.

Today, the challenge is even greater with the vast number of Web browsers available on so many

different platforms. Windows users can use Internet Explorer, Mozilla, and Opera; Macintosh

users have Internet Explorer, Mozilla, and now, Safari; Unix users can use Mozilla as well as

Konqueror. Developing for all of them requires a great deal of forethought and a well-planned

approach to dealing with their similarities and differences.

This chapter gives you an in-depth look at JavaScript browser and operating system detection to

prepare you to develop cross-browser solutions.

The Navigator Object

The most important object in client-side browser detection is the

navigator

object. The

naviga-

tor

object is one of the earliest BOM objects implemented (beginning in Netscape Navigator 2.0

and Internet Explorer 3.0). As I mentioned in Chapter 5, “JavaScript in the Browser,” it contains a

number of properties that can give you information about the browser, such as the name, version,

and platform.

Although Microsoft objected to the term

navigator

as being specific to Netscape’s browser, the

navigator

object has become a sort of de facto standard for providing information about a Web

browser. (Microsoft does have its own object called

clientInformation

in addition to the

navigator

object, but they both provide similar data.)

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