JSFiddle - React, Tailwind, and code Playground

HTML

<input type="button" value="按钮" id="btn1">
<div id="div1"></div>

CSS

#div1{
            width:100px;
            height:200px;
            border:1px solid red;
            display: none;
        }

JavaScript

var oBtn=document.getElementById('btn1');
            var oDiv=document.getElementById('div1');

            oBtn.onclick=function(ev){
                var oEvent=ev||event;
                //阻止当前事件函数事件冒泡
               
                oDiv.style.display='block';
            }
            document.onclick=function(){              
                setTimeout(function(){//观察事件冒泡：div出现一秒钟后隐藏了
                    oDiv.style.display='none';
                },1000);
            }