What are JQuery's advantages and what are disadvantages

What are JQuery's advantages and what are disadvantages

Hi, everybody
I am a Vietnamese student. I am learning JQuery. It is great. But i have a question
If i using event like this
 $(document).ready(function() {
 $("a").click(function() {
 alert("Hello world!");
 });
 });




for all of elements not just "a". Is it slow when compared with

<a onclick="alert('Hello world!')"></a>

I need to know



 what are advantages and what are disadvantages
Thanks for reading. I love you and JQuery