I'm pretty sure you're thinking about https://github.com/jquery/jquery/pull/1046#issuecomment-10723592, which I'm loathe to put in the style guide because "whatever's smallest" (my driving factor) can change over time with the vagaries of minification and compression.

But at the moment, `i = collection.length; while ( i-- )` and `for ( ; i < len; i++ )` are almost always the best choices, with the latter being necessary for cases where forward iteration is required.