Separation of browser-specific code

Separation of browser-specific code


A technic often used in javascript is the downloading of a different
script for each web browser, to avoid unuseful code.
Isn't there a way to create one file per renderer in jquery, like
jquery.trident.js
jquery.gecko.js
jquery.webkit.js
jquery.gecko-webkit.js
...
jquery.all.js
And put the specific codes in the right scripts, a develop a merging
tool to create the actual jquery.js script ?
It would permit user to choose to download the whole script or only
the necessary code.
Regards,
Ludovic