On Wed, Jul 28, 2010 at 1:20 PM, zhao Matt <mattzhao...@gmail.com> wrote: > Quote: > "The async and defer attributes are boolean attributes that indicate how the > script should be executed."..."The defer attribute may be specified even if > the async attribute is specified" > Do it mean 'async' is equivalent to 'defer'? (namely, are the two attributes > interchangeable?)
No. It just means that you can specify both, like <script async defer src="myscript.js"></script>. In this case, "async" takes precedence and "defer" is ignored in conforming browsers. > Quote: > "The defer and async attributes must not be specified if the src attribute > is not present." > Do it mean "if the src attribute is not present, the defer and async > attributes can be not used" ? (English is not my native language, :) ) Yes. I don't know why defer isn't allowed here -- maybe someone else knows the answer.
