直接上实例代码：
<img id="brandIcon" src="" />
<script language="JavaScript" type="text/javascript" >
function setBeerIcon() {
var classimg = $("#beer").find("option:selected").attr('data-img');
$("#brandIcon").attr("src",classimg);
}
</script>
<form>
<select id="beer" onChange="setBeerIcon();"
<option value="1" data-img="/img/1.jpg">项目一</option>
<option value="2" data-img="/img/2.jpg">项目二</option>
<option value="3" data-img="/img/3.jpg">项目三</option>
</select>
</form>
