js中的运动

缓慢隐藏与出现

效果：

鼠标移至分享上黄色区域自动向左隐藏。

<!DOCTYPE html>
<html>
<head>
    <title></title>
    <style type="text/css">
        div{
            background-color: yellow;
            height: 200px;
             150px;
            position: absolute;
            top:50px;
            left: -150px;
        }
        span{
            background-color: red;
            position: absolute;
            top:80px;
            left: 150px;
        }
    </style>
    <script type="text/javascript">

    window.onload = function(){
        var oDiv = document.getElementsByTagName('div')[0];
        oDiv.onmouseout = function(){
            startMove(-150);
        }
        oDiv.onmouseover = function(){
            startMove(0);
        }
    }

    var timer = null;
    function startMove(target){
        var oDiv = document.getElementsByTagName('div')[0];
        var speed = 10;
        if(oDiv.offsetLeft>target)
            speed = -10;
            //防止定时器被多次调用
        clearInterval(timer);
        timer = setInterval(function(){
            if(oDiv.offsetLeft != target){
                oDiv.style.left = oDiv.offsetLeft+speed+'px';
            }
            else
                clearInterval(timer);
        }, 30);
    }
    </script>
</head>
<body>
   <div><span>分享</span></div>
</body>
</html>

使用绝对定位，通过获取offsetLeft(相对于浏览器左边框的距离)的值和left来确定黄色区域的位置

图像透明度渐变效果

当鼠标移入图像时颜色变亮，移除时颜色变暗

<!DOCTYPE html>
<html>
<head>
    <title></title>
    <style type="text/css">
        div{
            background-color: yellow;
            height: 200px;
             150px;
            filter:alpha(opacity:30);
            opacity: 0.3;
        }
    </style>
    <script type="text/javascript">

    window.onload = function(){
        var oDiv = document.getElementsByTagName('div')[0];
        oDiv.onmouseout = function(){
            startMove(30);
        }
        oDiv.onmouseover = function(){
            startMove(100);
        }
    }

    var timer = null;
    var alpha = 30;
    function startMove(target){
        var oDiv = document.getElementsByTagName('div')[0];
        var speed = 10;
            //防止定时器被多次调用
        if(alpha > target)
            speed = -10;
        clearInterval(timer);
        timer = setInterval(function(){
            if(alpha != target){
                alpha += speed;
                oDiv.style.filter = "alpha(opacity:"+alpha+")";
                oDiv.style.opacity = alpha/100;
            }
            else
                clearInterval(timer);
        }, 30);
    }
    </script>
</head>
<body>
   <div></div>
</body>
</html>