var timer = null;
var d = 0;

(function($) {
    $.fn.maskedSlider = function(options) {
        var defaults = {delay:0,duration: 0};
        var options = $.extend(defaults, options);
        var element = $(this).attr("id");
        var elementWidth = $(this).width();
        var elementHeight = $(this).height();
        var topDivId = element + "_top";
        var bottomDivId = element + "_bottom";
        //延滞
        d = options.delay;
		var dura = options.duration + d;
		
        $(this).css("position", "relative").append("<div id='" + topDivId + "'></div>").append("<div id='" + bottomDivId + "'></div>");

        $("#" + topDivId).css({"position": "absolute","opacity": 1,"-moz-opacity": 1,"-khtml-opacity": 1,"left": 0,"top": 0});
        $("#" + bottomDivId).css({"position": "absolute","background-color": '#ffffff',"opacity": 1,"-moz-opacity": 1,"-khtml-opacity": 1});
        $("#" + bottomDivId).css({"height": elementHeight,"width": elementWidth - 0,"left": 0,"top": 0});
        timer = setTimeout(function() {
            $("#" + bottomDivId).delay(500).animate({width: 0, left: 0 + elementWidth}, dura , function(){clearTimeout(timer);timer = null;});
        });};
})(jQuery);