- style.filter = (style.filter || "").replace( ralpha, "" ) +
- (parseInt( value ) + '' === "NaN" ? "" : "alpha(opacity=" + value * 100 + ")");
+ var opacity = parseInt( value, 10 ) + '' === "NaN" ? "" : "alpha(opacity=" + value * 100 + ")";
+ var filter = style.filter || jQuery.curCSS( elem, 'filter' ) || "";
+ style.filter = ralpha.test(filter) ? filter.replace(ralpha, opacity) : opacity;