The YUI Global Object: Browser Detection with UA
This example demonstrates the use of UA to identify
the user's browser and to branch JavaScript logic based on what browser is
being used. (Note: We strongly recommend using feature
detection rather than user-agent sniffing to fork code; only use this technique
where it is absolutely necessary to do so — for example, in cases where
browsers do not report their own capabilities accurately.)
UA properties set for your browser:
First, a word of caution
Please DO NOT use this in place of feature detection. 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.
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.
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.
What UA looks like
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.
There's more information on the UA object and value
ranges in the API
Documentation.
Instantiate YUI
User Agent Info
In this simple example, we use the each to iterate the UA object.