Think again if you’re writing selectors such as
$("div#myId") |
When selecting against the DOM ID the fastest way to get the node is to use only the id:
$("#myId") //will translate into document.getElementById("myId") internally |
otherwise jQuery will first get all DIV-nodes then manually iterate over them looking for an attribute id that’s equal to “myId”. In a case with a large DOM-tree this could be a large performance-hit making your site unusable on slower computers if you’re using selectors like this everywhere.
On the other hand when selecting against CSS-classes it’s faster to use
$("div.myClass") |
than just
$(".myClass") |