Is using nth Child selectors in jQuery dependent on browser support for CSS3?

Question

Or is it safe to use when IE6/IE7 are heavily in use?

Answer 1

The whole idea behind jQuery is that it normalizes behavior among browsers. Everything is supposed to work fine on any browser on the "compatible" list, which includes IE6 and upwards.

However, note that browsers may be added to or dropped from the compatible list in the future; for example, jQuery 2.0 will only support IE 9 or later.