下拉菜单select+if判断语句实现下拉菜单联动

<script>
    function test(obj){
        if (obj.value == "zhangfei"){
            document.getElementById("tmp").style.display="block";
        }else{
            document.getElementById("tmp").style.display="none";
        }
    }
</script>

<label>用户</label>
<select id="uu" onchange="test(this)">
    <option>--请选择--</option>
    <c:forEach items="${users}" var="u">
        <option value="${u.name}">
            ${u.name};
        </option>
    </c:forEach>
</select>

<label id="tmp" style="display: none">zhangfei被选到了</label>