code: function removeClass(className) {
    if(!className) {
      // remove all classes from all matched elements
      this.each(function(el) {
        el.removeAttribute(attr);
      });
      return this;
    }
    var classes = className.split(/\s+/);
    this.each(function(el) {
      var val = el.getAttribute(attr);
      // no class attribute - nothing to remove
      if(!val) {
        return;
      }
      var names = val.split(/\s+/);
      names = names.filter(function(nm) {
        return ~classes.indexOf(nm) ? false : nm;
      });
      el.setAttribute(attr, names.join(' '));
    });
    return this;
  }
docs: Remove a single class, multiple classes, or all classes from
  each element in the set of matched elements.