javascript控制鼠标中键滑动

MouseWheel.js的代码如下：

var MouseWheel_Count=0;
function MouseWheel$handle(delta){
	MouseWheel_Count++;
	if(MouseWheel_Count>1)	return;
    if (delta < 0) //小于0向下滚动，大于0向上滚动
       //        alert("向下滚动");
    else 
       //        alert("向上滚动");
	setTimeout("MouseWheel$CountMinus();",500);
}

function MouseWheel$CountMinus()
{
	MouseWheel_Count=0;
}

/** 事件句柄
 */
function MouseWheel$wheel(event){
    var delta = 0;
    if (!event) /* For IE. */ 
        event = window.event;
    if (event.wheelDelta) { /* IE或者Opera. */
        	delta = event.wheelDelta/120;
//        delta = event.wheelDelta;
        /** 在Opera9中，事件处理不同于IE
         */
        if (window.opera) 
            delta = -delta;
    }
    else 
        if (event.detail) { /** 兼容Mozilla. */
            /** In Mozilla, sign of delta is different than in IE.
         * Also, delta is multiple of 3.
         */
            delta = -event.detail / 3;
        }
    /** 如果 增量不等于0则触发
     * 主要功能为测试滚轮向上滚或者是向下
     */
    if (delta) 
        MouseWheel$handle(delta);
}