如何使用过滤器：

var ps = $('p');
 
//Removes all elements from the set of matched elements that do 
//not match the specified function.
ps = ps.filter(function() {
  //return true to keep it,false to discard it
  //the logic is up to you.
});

要么

var ps = $('p');
 
//Removes all elements from the set of matched elements that 
//do not match the specified expression(s).
ps = ps.filter('.selector');

如何使用不：

var ps = $('p');
 
//Removes elements matching the specified expression 
//from the set of matched elements.
ps = ps.not('.selector');