You can add multiple classes by using addClass("foo bar"), therefore removeClass should work similar, eg. removeClass("bar foo")

removeClass: function(c){
  c = c.split(' ');
  if(c.length > 1)
    for(var i=0, s; s = c[i]; i++)
      jQuery.className.remove(this, s);
  else
    jQuery.className.remove(this, c[0]);
}

toggleClass would work similar:

toggleClass: function( c ){
  var checkClass = function(element, c) {
    jQuery.className[ jQuery.className.has(element,c) ? "remove" : "add" ](element,c);
  };
  c = c.split(' ');
  if(c.length > 1)
    for(var i=0, s; s = c[i]; i++)
      checkClass(this, s);
  else
    checkClass(this, c[0]);
}

Is there a bette way to implement those? Maybe add stuff to jQuery.className that handles multiple names and can be used by both remove and toggle?

Back when removeClass used a regexp this came for free because you could say .removeClass("(class1|class2)") to remove class1 and class2. I guess the split/splice approach was benchmarked as being a lot faster?

This was never the intended functionality of .addClass()/.removeClass()/.toggleClass(). Adding multiple classes using addClass should be deemed unexpected, and undocumented, until otherwise noted.

Resolved in SVN.