无缝滚动改进版支持上下左右滚动（封装成函数）_javascript技巧

   
   
   


   



           

/**********
    功能：实现水平或垂直无缝滚动
    参数：direction方向，总共4个值：left,right,top,bottom
          speed移动距离
          iTime多少时间后开始移动，若不写则页面加载完开始移动
**********/
function scroll(direction,speed,iTime){
    var oDiv = document.getElementById('scroll');
    var oUl = oDiv.getElementsByTagName('ul')[0];
    var aLi = oDiv.getElementsByTagName('li');
    var aBtn = oDiv.getElementsByTagName('a');
    var timer = null;
    var iSpeed = 0;
    var flag = true;    //判断水平移动还是垂直移动

    oUl.innerHTML += oUl.innerHTML;

    switch(direction){
        case 'left':
            iSpeed = -speed;
            oUl.style.width = aLi[0].offsetWidth * aLi.length + 'px';
            flag = true;
            break;
        case 'right':
            iSpeed = speed;
            oUl.style.width = aLi[0].offsetWidth * aLi.length + 'px';
            flag = true;
            break;
        case 'top':
            iSpeed = -speed;
            flag = false;
            break;
        case 'bottom':
            iSpeed = speed;
            flag = false;
            break;
    };

    setTimeout(move,iTime);

    //左按钮和上按钮
    aBtn[0].onclick = function(){
        clearInterval(timer);
        iSpeed = -speed;
        move();
    };

    //右按钮和下按钮
    aBtn[1].onclick = function(){
        clearInterval(timer);
        iSpeed = speed;
        move();
    };

    oUl.onmouseover = function(){
        clearInterval(timer);
    };

    oUl.onmouseout = function(){
        move();
    };

    function move(){   
        timer = setInterval(function(){
            if(flag){
                oUl.style.left = oUl.offsetLeft + iSpeed + 'px';
                if(oUl.offsetLeft                     oUl.style.left = '0';
                }else if(oUl.offsetLeft > 0){
                    oUl.style.left = - oUl.offsetWidth / 2 + 'px';
                }
            }else{
                oUl.style.top = oUl.offsetTop + iSpeed + 'px';
                if(oUl.offsetTop                     oUl.style.top = '0';
                }else if(oUl.offsetTop >= 0){
                    oUl.style.top = - oUl.offsetHeight / 2 + 'px';
                };
            };
        },30);
    };
};