(function($) {
$.fn.xslider = function(settings) {
settings = $.extend({}, $.fn.xslider.defaults, settings);
this.each(function() {
var scrollobj = settings.scrollobj || $(this).find("ul");
var maxlength = settings.maxlength || (settings.dir == "H" ? scrollobj.parent().width() : scrollobj.parent().height()); //length of the wrapper visible;
var scrollunits = scrollobj.find("li"); //units to move;
var unitlen = settings.unitlen || (settings.dir == "H" ? scrollunits.eq(0).outerWidth() : scrollunits.eq(0).outerHeight());
var unitdisplayed = settings.unitdisplayed; //units num displayed;
var nowlength = settings.nowlength || scrollunits.length * unitlen; //length of the scrollobj;
var offset = 0;
var sn = 0;
var movelength = unitlen * settings.movelength;
var moving = false; //moving now?;
var btnright = $(this).find("a.aright");
var btnleft = $(this).find("a.aleft");

if(settings.dir == "H") {
scrollobj.css("left", "0px");
} else {
scrollobj.css("top", "0px");
}
if(nowlength > maxlength) {
btnleft.addClass("agrayleft");
btnright.removeClass("agrayright");
offset = nowlength - maxlength;
} else {
btnleft.addClass("agrayleft");
btnright.addClass("agrayright");
}

btnleft.click(function() {
if($(this).is("[class*=‘agrayleft‘]")) {
return false;
}
if(!moving) {
moving = true;
sn -= movelength;
if(sn > unitlen * unitdisplayed - maxlength) {
jQuery.fn.xslider.scroll(scrollobj, -sn, settings.dir, function() {
moving = false;
});
} else {
jQuery.fn.xslider.scroll(scrollobj, 0, settings.dir, function() {
moving = false;
});
sn = 0;
$(this).addClass("agrayleft");
}
btnright.removeClass("agrayright");
}
return false;
});
btnright.click(function() {
if($(this).is("[class*=‘agrayright‘]")) {
return false;
}
if(!moving) {
moving = true;
sn += movelength;
if(sn < offset - (unitlen * unitdisplayed - maxlength)) {
jQuery.fn.xslider.scroll(scrollobj, -sn, settings.dir, function() {
moving = false;
});
} else {
jQuery.fn.xslider.scroll(scrollobj, -offset, settings.dir, function() {
moving = false;
}); //滚动到最后一个位置;
sn = offset;
$(this).addClass("agrayright");
}
btnleft.removeClass("agrayleft");
}
return false;
});

if(settings.autoscroll) {
jQuery.fn.xslider.autoscroll($(this), settings.autoscroll);
}

})
}
})(jQuery);

jQuery.fn.xslider.defaults = {
maxlength: 0,
scrollobj: null,
unitlen: 0,
nowlength: 0,
dir: "H",
autoscroll: null
};
jQuery.fn.xslider.scroll = function(obj, w, dir, callback) {
if(dir == "H") {
obj.animate({
left: w
}, 500, "easeInSine", callback);
} else {
obj.animate({
top: w
}, 500, "easeInSine", callback);
}
}
jQuery.fn.xslider.autoscroll = function(obj, time) {
var vane = "right";

function autoscrolling() {
if(vane == "right") {
if(!obj.find("a.agrayright").length) {
obj.find("a.aright").trigger("click");
} else {
vane = "left";
}
}
if(vane == "left") {
if(!obj.find("a.agrayleft").length) {
obj.find("a.aleft").trigger("click");
} else {
vane = "right";
}
}
}
var scrollTimmer = setInterval(autoscrolling, time);
obj.hover(function() {
clearInterval(scrollTimmer);
}, function() {
scrollTimmer = setInterval(autoscrolling, time);
});
}

//图片的左右滑动

找了份插件，，求个大神帮忙标下注释。。。