<div class="intro">
<p>This example demonstrates how to access YUI's built-in user-agent
information to learn things about the environment in which your code
is running.  This includes information like what browser, version, and
operating system are being used; it also includes context information
like whether you're code is running on a mobile browser, running in a
secure page, or running under Adobe Air or Google Caja.</p>  

<p><strong>Note:</strong> We strongly recommend using feature
detection rather than user-agent sniffing to fork code. Fork on the
user-agent information only when absolutely necessary to do so (for 
example, in cases where browsers do not report their own capabilities
accurately).</p>
</div>

<div class="example">
    {{>yui-ua}}
</div>

<h3>First, a word of caution</h3>

<p><strong>Please DO NOT use this in place of feature detection</strong>.
Though many browsers have known JavaScript implementation quirks, it is bad
practice and unsafe coding to make the assumption that because the page is being
viewed in browser X that you can rely on feature Y being available.  Check for
feature Y if you need it.</p>

<p>Browser sniffing is an imprecise science, and relies on many things in the
browser environment to be just right.  Though many techniques are very
accurate, 100% accuracy can't be guaranteed.</p>

<p>Use the `UA` object to inform you of what browser your
page is being viewed in, but avoid using this technique unless feature detection
will not serve your purpose.</p>

<h3>What UA looks like</h3>

<p>`UA` is an object literal containing keys for most major user
agents.  The key corresponding to the current browser is assigned a version
number.  All others have value 0, with the exception of the `mobile`
property, which is a string value indicating the name of a supported mobile 
device that was detected or null.</p>

```
if (Y.UA.gecko > 0) {}  // e.g. Firefox
if (Y.UA.ie > 0) {}     // Microsoft Internet Explorer

// Or leverage boolean coercion -- 0 evaluates as false
if (Y.UA.opera) {}  // Opera
if (Y.UA.webkit) {} // Safari, Webkit
```

<p>There's more information on the `UA` object and value
ranges in the API Documentation.</p>

<h3>Instantiate YUI</h3>

```
YUI().use('node', function(Y) {
    // This method is in the core of the library, so we don't have to use() any
    // additional modules to access it.  However, this example requires 'node'.
```

<h3>User Agent Info</h3>
<p>In this simple example, we use the `each` to iterate the `UA` object.</p>

```
{{>yui-ua-js}}
```
