Jerry Stuckle wrote:
> Gilles Ganault wrote:
>> On Sun, 17 Feb 2008 12:31:17 -0800, Animesh K <animesh1978@gmail.com>
>> wrote:
>>> I am not sure about the back-end, but at the front end, Facebook uses
>>> Php and JS. Signing in takes you to the page below. Facebook's
>>> popularity can be judged at Alexa.
>>
>> BTW, if I include some JS libraries/components in each page, are they
>> cached by the browser so that it doesn't need to download those files
>> again the next time?
>>
>
> Maybe, maybe not. It depends on the browser, the options the user has
> set, and even possible caching by ISP's between you and the client.
>
> The only think you know for sure is it's something you have absolutely
> no control over.
>

Well your worst-case point of not knowing is valid, but for a large
fraction of users, caching (up to about 50MB or more) is enabled by
default. Most people use IE 6 or IE 7. Even those who move to firefox
don't go to advanced settings.