It depends on what you're trying to do. Mostly, I try to write code that displays the same in every possible browser without special-casing or using confusing i

It depends on what you're trying to do. Mostly, I try to write code that displays the same in every possible browser without special-casing or using confusing idioms. CPU cycles are cheap. A webpage that loads a little slow is a possible lost sale. A webpage that fails to load is a definite lost sale.