javascript

Client Detection
Although browser vendors have made a concerted effort to implement common interfaces, the fact
remains that each browser presents its own capabilities and flaws. Browsers that are available
cross - platform often have different issues even though they are technically the same version. These
differences force web developers to either design for the lowest common denominator or, more
commonly, use various methods of client detection to work with or around limitations.
Client detection remains one of the most controversial topics in web development. The idea that
browsers should support a common set of functionality pervades most conversations on the topic.
In an ideal world, this would be the case. In reality, however, there are enough browser differences
and quirks that client detection becomes not just an afterthought, but also a vital part of the
development strategy.
There are several approaches to determine the web client being used, and each has advantages and
disadvantages. It ’ s important to understand that client detection should be the very last step in
solving a problem; whenever a more common solution is available, that solution should be used.
Design for the most common solution first and then augment it with browser - specific solutions later.
Capability Detection
The most commonly used and widely accepted form of client detection is called capability detection .
Capability detection (also called feature detection) aims not to identify a specific browser being
used, but rather to identify the browser ’ s capabilities. This approach presumes that specific
browser knowledge is unnecessary and that the solution may be found by determining if the
capability in question actually exists. The basic pattern for capability detection is as follows:
if (object.propertyInQuestion){
//use object.propertyInQuestion
}