<style>
.nodeSmall {
width: 50px;
height: 50px;
background: url(../img/bgs.png) no-repeat -159px -51px;
position: fixed;
right: 10px;
top: 40%;
}
.erweima {
position: absolute;
top: 0;
left: -150px;
}
.nodeSmall a {
display: block;
width: 50px;
height: 50px;
}
.hide {
display: none;
}
.show {
display: block;
}
</style>
</head>
<body>
<div class="nodeSmall" id="node_small">
<a href="#"></a><!--锚定-->
<div class="erweima hide" id="er">
<img src="../img/456.png" />
</div>
</div>
<script>
function lss(id) {
return document.getElementById(id);
}
var aObj=lss("node_small").getElementsByTagName("a")[0];
//为a注册鼠标进入
aObj.onmouseenter=function () {
lss("er").className="erweima show";
};
//为a注册鼠标离开
aObj.onmouseout=function () {
lss("er").className="erweima hide";
};
</script>
原文：https://www.cnblogs.com/lujieting/p/10046467.html