jquery的curCSS方法

curCSS = function( elem, name ) {
    var ret, 
        computed = window.getComputedStyle( elem, null ),
        style = elem.style;

    if ( computed ) {
        //getPropertyValue兼容ie9获取filter:Alpha(opacity=50)
        ret = computed.getPropertyValue( name ) || computed[ name ];

        //如果是动态创建的元素，则使用style方法获取样式
        if ( ret === "" && !jQuery.contains( elem.ownerDocument, elem ) ) {
            ret = jQuery.style( elem, name );
        }

            
        .................
    }

    return ret;
};