browscap ini directive not set

I don’t think this is the “best” solution to detect is a browser supports what you need for your website :

• first of all, browsers can lie — they can send whatever thay want as User-Agent
  • And even if a given version of a support should support what you need, Javascript can still be disabled.
• second, there are more “proper” way to detect what a browser can do or not, when it comes to Javascript.

For the second point, you should test if the browser actually supports what you need — and not rely on a list such as the browscap one.

Still, to answer your question about browscap : there is a note at the bottom of the manual page for get_browser that says (quoting) :

Note: In order for this to work, your browscap configuration
setting in php.ini must point to the
correct location of the browscap.ini
file on your system. browscap.ini is
not bundled with PHP, but you may find
an up-to-date »
php_browscap.ini file here.

While browscap.ini contains
information on many browsers, it
relies on user updates to keep the
database current. The format of the
file is fairly self-explanatory.

So, you have to :

• download the browscap file,
• and set the browscap directive in your php.ini file, so it points to the file you downloaded.