SOURCE

/*
* 处理方法
*/
const showCard = (activeId)=>{
    document.querySelectorAll(`.user`).forEach(item=>item.style.display = 'none');
    document.querySelector(`.${activeId}`).style.display = 'block';
}

// 初始化以及选择的时候触发
const select = document.querySelector('select');
select.onchange = ({target:{value}})=>showCard(value);
showCard(select.value)

<select>
    <option value="dsh">丁少华</option>
    <option value="wx">王新</option>
</select>
<div class="dsh user">丁少华123</div>
<div class="wx user">王新456</div>