SOURCE

console 命令行工具 X clear

                    
>
console
var flag = 0;
function showmenu(id) {
  var list = document.getElementById("list" + id);
  var menu = document.getElementById("menu" + id) ;
  if (flag != 0 && flag != id) {
    document.getElementById("list" + flag).style.display = "none";
  }
  if (list.style.display == "none") {
    document.getElementById("list" + id).style.display = "block";
    flag = id;
  } else {
    document.getElementById("list" + id).style.display = "none";
    flag = 0;
  }
}
<body>
  <div id="nav">
    <div class="title" id="menu1" onclick="showmenu('1') ">
      <b>
        系统维护
      </b>
    </div>
    <div id="list1" class="content" style="display:none">
      <ul>
        <li>
          地址设置
        </li>
        <li>
          环境参数
        </li>
        <li>
          标题设置
        </li>
      </ul>
    </div>
    <div class="title" id="menu2" onclick="showmenu('2')">
      <b>
        人事管理
      </b>
    </div>
    <div id="list2" class="content" style="display:none">
      <ul>
        <li>
          人员信息
        </li>
        <li>
          部门维护
        </li>
      </ul>
    </div>
    <div class="title" id="menu3" onclick="showmenu('3')">
      <b>
        信息查询
      </b>
    </div>
    <div id="list3" class="content" style="display:none">
      <ul>
        <li>
          部门查询
        </li>
        <li>
          人员查询
        </li>
        <li>
          日志查询
        </li>
      </ul>
    </div>
  </div>
</body>
* {
  margin: 0;
  padding: 0;
  list-style: none;
  font-size: 14px
}

#nav {
  margin: 10px;
  text-align: center;
  line-height: 25px;
  width: 200px;
}

.title {
  background: #4169E1;
  color: #fff;
  border-bottom: 1px solid #fff;
  cursor: pointer;
}

.title1 {
  background: #888;
  color: #000;
  border-bottom: 1px solid #666;
  cursor: pointer;
}

.content li {
  color: #336699;
  background: #ddd;
  border-bottom: 1px solid #fff;
  font: font-family: "Times New Roman", Georgia, Serif;
}

li:hover {
  background-color: #4682B4;
}