[squid-users] how to influence the generation of cached objects's key?

hello, all:

in one squid, there are many web sites, but some static files have the
same content. and by default, squid would cache the same-content files
many times, which would decrease the storage usage.

in order to make use of storage, it is better to save the same-content
file only one time.

to achieve that, I want to affect the key generation of cached object.

that is, given the two url of "www.a.com/sale/someFunction.js" and
"www.a.com/sale/someFunction.js", and the javascript (someFunction.js)
files have the same content.

with squid, can I "cut" the part before "someFunction.js" when the url
is given to generate cached object's key?

thanks in advance!

-- 
Best Regards
rmn190