你说的是这样？

html

<div id="show" style="display:none;">哦</div>
<button id="btn">点我啊</button>

js

var timeoutHandler = null;
document.getElementById('btn').onclick = function(){
     var show = document.getElementById('show');
     if(timeoutHandler){
         clearTimeout(timeoutHandler);
     }
     show.style.display = 'block';
     timeoutHandler = setTimeout(function(){
         show.style.display = 'none';
     },5000);
};