介绍三个不常用的HTML元素：<details>、<summary>、<dialog>

<button>显示对话框</button>
<dialog>我是对话框的内容</dialog>
<script>
var oBtn = document.getElementsByTagName(&#39;button&#39;)[0];
var oDia = document.getElementsByTagName(&#39;dialog&#39;)[0]; 
oBtn.onclick = function(){
  console.log(oDia.getAttribute(&#39;open&#39;))
  if(!oDia.getAttribute(&#39;open&#39;)){
    oDia.setAttribute(&#39;open&#39;,&#39;open&#39;);
    this.innerHTML =&#39;隐藏文本框&#39;;
  }else{
    oDia.removeAttribute(&#39;open&#39;);
    this.innerHTML = &#39;显示文本框&#39;;
  }
}
</script>