<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
<style>
img{
width:25px;
}
</style>
</head>
<body>
<img src="img/index.png"/>
<select >
<option value="img/index.png">首页</option>
<option value="img/logo.png">动漫</option>
<option value="img/select.png">电影</option>
<option value="img/loading.gif">博客</option>
</select>
<script>
var main=document.querySelector("select");
var img=document.querySelector("img");
main.onchange=function(){
img.setAttribute("src",this.value);
}
</script>
</body>
</html>