Script ua.js (anew)

The original script was published in 2002. It hasn't been updated since 2003. This is an attempt to revive the basic concept and make the script useful anew.

Source

ua.js

Background

The script's source file is a Contributor Version of the source file formerly located at <http://devedge.netscape.com/toolbox/examples/2002/xb/ua/ua.js> but then (temporarily) moved to <http://devedge-temp.mozilla.org/toolbox/examples/2002/xb/ua/ua.js>.
Below is the description quoted in full from the original manpage:

xbDetectBrowser() is called when the script ua.js is loaded. It sets several properties on the window.navigator object which detail the kind of browser being used as based upon the reported navigator.userAgent string.

Please note that Object based sniffing is preferrable in most cases to using detection based upon the navigator.userAgent string. Many browsers, Gecko and Opera for example, can be configured to report any User Agent String. Opera even changes the DOM they support depending upon whether the user has set their User Agent string to an IE compatible setting. In addition, Object based sniffing will support any Browser which supports the approprioate objects while User Agent string based sniffing will only detect specific browsers.

However, there are situations, for example when you need to distinguish between versions of the same browser, where User Agent string based sniffing is appropriate.

Changes

The major changes in the new 2006-2007 edition are listed here:

The property navigator.OS will stay undefined, since the underlying navigator.platform property does not exist in JavaScript applications until language version 1.2. Furthermore, this is not a property of the browser, but rather of the environment.
The property navigator.org will stay undefined.
The property navigator.version will still return a floating point number, however it is computed differently. Cp. the listing further down.
Some possible values of the property navigator.family are removed or modified, while others are added. Cp. the listing further down.
A few more properties are set on the navigator object.

Example

This script application example will render a table to show the name, value, a short description and type of each property created by the script.

Settings by ua.js

`function xbDetectBrowser()`

This function should work with all browsers complying with JavaScript from language version 1.0, i.e. Netscape Navigator 2, Internet Explorer 3, Opera 3 etc. When the source code is placed in – or the source file called from – the <head> section of a document, it is initiated before the document <body> has begun to load.

`navigator` properties added

There are nine properties added on the window.navigator object, but three of those are kept for backwards compatibility only and are therefore struck through in the listing.

The families and kinship relations

Due to shared or similar program source code, the main browsers are grouped into so-called families, browsers belonging to a particular family presumed to behave consistently from a web designer’s point of view. Different versions of a browser within a family can be distinguished by the navigator.version property.

Some of the "old" families are by now as well to be considered obsolete, but we keep them for backwards compatibility in the ~~navigator.family~~ property. A more relevant concept is the rendering engine used by a particular browser. We currently distinguish between Gecko, Trident, Presto and Apple Web Kit engines, which are covered by the navigator.engine property. If the browser is not built around one of those rendering engines, the property will fall back upon the family name.

A few vendors (notably Opera) are using the always applicable navigator.appName and navigator.appVersion properties for spoofing purposes. Occasionally there might be a benefit to let the script believe in the spoof. The navigator.kin property is simply combining those predefined properties to identify the application.

navigator.kin

Returns a string resolved by the concatenation

navigator.appName + '/' +
        parseInt(navigator.appVersion)

. This way the resulting string would be "Microsoft Internet Explorer/4" if Internet Explorer was used. To simplify matters, the script will instead return "MSIE/4". A few examples:

"MSIE/4" Internet Explorer 4 and later and also Opera spoofing as Internet Explorer
"Netscape/4" Netscape Navigator 4
"Netscape/5" Browsers belonging to the Gecko family such as Netscape 6 and later, Firefox, SeaMonkey, and Safari and other browsers applying the Apple Web Kit
"Opera/N" Opera browsers (if spoofing is not used) where "N" represents the application version number integer 3, 4, 5, ... 9.

~~navigator.family~~

Returns a string, which will be empty if the browser doesn't belong to one of the families listed. The formerly possible values hotjava and aol are removed. Possible values:

"gecko" browsers based upon mozilla.org open source code, e.g. Netscape 6+, Firefox, SeaMonkey, Galeon, K-Meleon
"opera" Opera browsers versions before 7
"presto" Opera browsers versions 7 and later
"applewebkit" browsers applying the AppleWebKit, e.g. Safari, OmniWeb
"ie3" Internet Explorer versions before 4
"ie4" Internet Explorer versions 4 and later, Netscape Browser 8 when the trident plugin is applied
"java" java based browsers, e.g. ICEbrowser, HotJava
"nnN " where "N" is a Netscape version major integer, usually nn2, nn3 or nn4
""

navigator.engine

Returns a string, which will be empty if the browser doesn't belong to a family as of above. Currently possible values:

"gecko" browsers based upon mozilla.org open source code, e.g. Netscape 6+, Firefox, SeaMonkey, Galeon, K-Meleon
"presto" Opera browsers versions 7 and later
"applewebkit" browsers applying the AppleWebKit, e.g. Safari, OmniWeb
"trident" Internet Explorer versions 4 and later, Netscape Browser 8 when the trident plugin is applied
same as ~~navigator.family~~

navigator.version

Returns a number, which will be a floating point number from the number part of the navigator.appVersion property, if the browser doesn't belong to one of the families listed or belongs to the "java" family. So, for browsers where ~~navigator.family~~ is other than empty, the property will be the navigator.engine related version number as seen in the list:

"gecko" browsers will return the build date from the navigator.productSub property, such as 20061010.
"opera" browsers return the normal version number.
"presto" browsers return the normal version number.
"applewebkit" browsers return the particular AppleWebKit build version number converted to double floating points.
"ie3" and "ie4" browsers return the JScript version number.
Netscape Communicator and earlier Netscape browsers return the normal version number.

Gecko specific version

Normally the "gecko" family browsers are stating a particular release version number in the user agent string, prepositioned by the abbreviation "rv:".

~~navigator.rv~~

Returns a string, which is identical with the release version number if it exists and the ~~navigator.family~~ value is gecko. If not, the property is empty:

e.g. "1.8.1"
""

navigator.rversion

Returns a number, which is the release version number in double floating points if the ~~navigator.rv~~ value is other than empty. If not, the property is 0.

e.g. 1.0801
0

Cosmetic properties

The script will scan the user agent string to find the best fit for the browser's popular (brand) name and version. The corresponding properties can be useful in alerts or short messages communicated to a web site's visitors.

navigator.prettyName: Returns a string, usually identical with the first or last word(s) of navigator.userAgent.
navigator.prettyVersion: Returns a string, which is identical with the number put in relation with navigator.prettyName.

The script engine

An innovation in the new edition of the ua.js script is the investigation into the capacities of the script engine. The corresponding property can be useful to prevent simpler script engines from trying to interpret too complex script code. A particular ~~navigator.js~~ value may be applied as a minimum condition instead of the <script> deprecated attribute language="javascript1.x" in HTML.

~~navigator.js~~

Returns a number for the evaluated client-side JavaScript language version up to version 1.3. (Testing beyond that point would necessarily break simpler script engines.)

1.3 The script engine is compliant with ECMAScript, edition 1, and has not undefined values for the call and apply methods of functions (and fulfills the 1.2 requirements below).
1.2 The script engine has not undefined values for navigator.platform and screen and has a way of determining the natural language of the browser or system (and fulfills the 1.1 requirements below).
1.1 The script engine has not undefined values for Date.prototype.getTimezoneOffset, navigator.javaEnabled, navigator.mimeTypes and navigator.plugins.
1.0 Netscape Navigator 2, Internet Explorer 3 applying JScript version 1
0 unknown version

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