# Yahoo! UI Library

### YAHOO Global 2.8.1

Yahoo! UI Library > yahoo > YAHOO.env.ua
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## `static` Class YAHOO.env.ua

Do not fork for a browser if it can be avoided. Use feature detection when you can. Use the user agent as a last resort. YAHOO.env.ua stores a version number for the browser engine, 0 otherwise. This value may or may not map to the version number of the browser using the engine. The value is presented as a float so that it can easily be used for boolean evaluation as well as for looking for a particular range of versions. Because of this, some of the granularity of the version info may be lost (e.g., Gecko 1.8.0.9 reports 1.8).

### Properties

#### air - `float`

Adobe AIR version number or 0. Only populated if webkit is detected. Example: 1.0

#### caja - `float`

Google Caja version number or 0.

#### gecko - `float`

Gecko engine revision number. Will evaluate to 1 if Gecko is detected but the revision could not be found. Other browsers will be 0. Example: 1.8

    Firefox 1.0.0.4: 1.7.8   <-- Reports 1.7
    Firefox 1.5.0.9: 1.8.0.9 <-- Reports 1.8
    Firefox 2.0.0.3: 1.8.1.3 <-- Reports 1.8
    Firefox 3 alpha: 1.9a4   <-- Reports 1.9

#### ie - `float`

Internet Explorer version number or 0. Example: 6

#### mobile - `string`

The mobile property will be set to a string containing any relevant user agent information when a modern mobile browser is detected. Currently limited to Safari on the iPhone/iPod Touch, Nokia N-series devices with the WebKit-based browser, and Opera Mini.

#### opera - `float`

Opera version number or 0. Example: 9.2

#### os - `static string`

The operating system. Currently only detecting windows or macintosh

#### secure - `static boolean`

Set to true if the page appears to be in SSL

#### webkit - `float`

AppleWebKit version. KHTML browsers that are not WebKit browsers will evaluate to 1, other browsers 0. Example: 418.9.1

    Safari 1.3.2 (312.6): 312.8.1 <-- Reports 312.8 -- currently the
    latest available for Mac OSX 10.3.
    Safari 2.0.2:         416     <-- hasOwnProperty introduced
    Safari 2.0.4:         418     <-- preventDefault fixed
    Safari 2.0.4 (419.3): 418.9.1 <-- One version of Safari may run
    different versions of webkit
    Safari 2.0.4 (419.3): 419     <-- Tiger installations that have been
    updated, but not updated
    to the latest patch.
    Webkit 212 nightly:   522+    <-- Safari 3.0 precursor (with native SVG
    and many major issues fixed).
    3.x yahoo.com, flickr:422     <-- Safari 3.x hacks the user agent
    string when hitting yahoo.com and
    flickr.com.
    Safari 3.0.4 (523.12):523.12  <-- First Tiger release - automatic update
    from 2.x via the 10.4.11 OS patch
    Webkit nightly 1/2008:525+    <-- Supports DOMContentLoaded event.
    yahoo.com user agent hack removed.

http://developer.apple.com/internet/safari/uamatrix.html

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