code: function( element, opacity, usesAlpha ) {
  
              var ieOpacity,
                  ieFilter;
  
              element = $.getElement( element );
  
              if ( usesAlpha && !$.Browser.alpha ) {
                  opacity = Math.round( opacity );
              }
  
              if ( $.Browser.opacity ) {
                  element.style.opacity = opacity < 1 ? opacity : "";
              } else {
                  if ( opacity < 1 ) {
                      ieOpacity = Math.round( 100 * opacity );
                      ieFilter  = "alpha(opacity=" + ieOpacity + ")";
                      element.style.filter = ieFilter;
                  } else {
                      element.style.filter = "";
                  }
              }
          }
docs: Sets the opacity of the specified element.
  @function
  @param {Element|String} element
  @param {Number} opacity
  @param {Boolean} [usesAlpha]