The navigator object in many ways represents the browser application. As such, the browser is outside the scope of the document object model. Even so, the navigator object plays an important role in scripting, because it allows scripts to see what browser and browser version is running the script. In addition to several key properties that both Navigator and Internet Explorer have in common, each browser also extends the property listing of this object in ways that would generally benefit all browsers. IE duplicates this object under the clientInformation object name, but for cross-browser compatibility, you can use the navigator object reference in all browsers.

Reveals the code name of the browser. Both Navigator and Internet Explorer return Mozilla, which was the code name for an early version of Navigator (a combination of the early freeware name of the Mosaic browser and Godzilla). The Mozilla character is Netscape's corporate mascot, but all browsers that license the original Mosaic technology (including IE) return Mozilla.

With succeeding generations of Internet Explorer, this property returns a dizzying range of values, most of which are not useful for typical version detection. IE 5.x for Windows returns an appVersion value of 4.0, with the appMinorVersion reporting the first digit to the right of the decimal. In IE 6 for Windows, the appMinorVersion returns a string signifying a build or patch code number, such as ;Q313675;. Use with extreme caution.

Reveals the model name of the browser.

Reveals a version number of the browser engine, along with minimal operating system platform information (a subset of the information returned by userAgent). Sample returned values are as follows.

Provides the default written language of the browser. The Navigator equivalent is the navigator.language property.

Returns whether the browser allows reading and writing of cookie data.

Returns a string reference of the CPU of the client computer. Common Intel microprocessors (including Pentium-class CPUs and Macintoshes running Windows emulators) return x86, while PowerPC Macintoshes return PPC. This value tells you only about the basic hardware class, not the operating system or specific CPU speed or model number.

Indicates the written language for which the browser version was created. The language is specified in the ISO 639 language code scheme (such as en-us). Internet Explorer provides this information via the navigator.browserLanguage property.

Returns an array of mimeType objects supported by installed plugins in the browser. IE for Windows provides this property for syntactical compatibility, but it always returns an array of zero length. See the mimeType object.

Specifies whether the browser is set for online or offline browsing (in Internet Explorer's File menu). Pages may wish to invoke live server actions when they load in online mode, but avoid these calls when in offline mode. Use this Boolean property to build such conditional statements.

Returns a string containing operating system or central processing unit information about the client machine. Values vary widely across systems. Windows clients are divided roughly into two categories: non-NT and NT. The former includes Windows 95, 98, and ME (oscpu values of Win95, Win98, and Win 9x 4.90, respectively). The NT category includes Windows NT 4 (WinNT4.0) and Windows XP (Windows NT x.x). Macintosh systems all report the CPU type and the absence or presence of Mac OS X (PPC or PPC Mac OS X). Unix systems report both the operating system and CPU type. The oscpu value is also a part of the userAgent value. Formatting for this information is not the same in Internet Explorer's corresponding cpuClass or userAgent properties.

Returns the name of the operating system or hardware platform of the browser. For Windows 95/NT, the value is Win32; for a Macintosh running a PowerPC CPU, the value is MacPPC. At least for the major platforms I've been able to test, Navigator and Internet Explorer agree on the returned values. Using this property to determine the baseline facilities of the client in a conditional expression can help the page optimize its output for the device.

Returns a collection of plugin objects recognized by the browser to facilitate script determination of the browser's support for a particular external media type. IE 4 and later for Windows implement this property, but only as a dummy placeholder that always returns an array of length zero. See the mimeType and plugin objects.

Return a string identifying the software engine behind the browser. In Netscape 6, the product property returns Gecko, while the productSub property returns a development build number (in string form).

Returns a string in Navigator 4 revealing the browser's encryption level (that is, the domestic or export encryption policy to which the browser adheres). With the loosening of U.S. encryption export laws, Netscape 6 implements one encryption type across all versions. In Netscape 6, this property returns an empty string.

Specifies the code for the default written language used by the operating system. If you have multi-lingual content available, you can use this property to insert content in specific languages.

Provides information about the browser software, including version, operating system platform, and brand. This is the most complete set of information about the browser, whereas appVersion and appName properties provide subset (and not always correct) data. Typical data for the userAgent property looks like the following examples from IE and Navigator:

Mozilla/4.0 (compatible; MSIE 6.0; Windows 98; Q312461)
Mozilla/5.0 (Macintosh; U; PPC; en-US; rv:0.9.4) Gecko/20011022 Netscape6/6.2

The default written language of the browser, based on the operating system user profile setting (if one exists). The property defaults to the browserLanguage property.

The userProfile property is, itself, an object that lets scripts request permission to access personal information stored in the visitor's user profile (for Win32 versions of Internet Explorer). See the userProfile object.

Return a string identifying the browser product that employs the Mozilla engine. In Netscape 6, the vendor property returns Netscape6, while Netscape 7 returns simply Netscape. The vendorSub property returns the version release in detail (in string form). If you want to test for a minimum version, convert the navigator.vendorSub value to a decimal floating-point number before performing a comparison against your minimum requirement.

Returns whether Java is turned on in the browser. This method obviously won't help you in a nonscriptable browser (or scriptable browser that doesn't support the property), but if scripting is enabled, it does tell you whether the user has Java turned off in the browser preferences.

By way of signed scripts in Navigator 4, you can access a wide variety of user preferences settings. These include even the most detailed items, such as whether the user has elected to download images or whether style sheets are enabled. Most of these settings are intended for scripts used by network administrators to install and control the user settings of enterprise-wide deployment of Navigator. Consult the Netscape developer web site for further information about these preferences settings (http://developer.netscape.com/docs/manuals/communicator/preferences/). Netscape 6 throws a security exception when invoking this method (even with signed scripts), but the method works with signed scripts in Netscape 7.

Returns whether data tainting is turned on in the browser. This security mechanism was never fully implemented in Navigator, but the method that checks for it is still included in newer versions of Navigator for backward compatibility. Internet Explorer also includes it for compatibility, even though it always returns false.