在js代码 里增加 div 的问题

Question

<div style='display:none' id='div_a'>
  <input type='file' id='file1'/>
  <button type="button" value="确定" class="Button">确定</button>
  </div>
<script>
var str = "<div id='div_Dialog' style='BACKGROUND:#fff;padding:10px;border: #336699 2px solid;position: absolute;font-size:12px;TEXT-ALIGN: left;line-height:22px;position: absolute;font-size:12px;z-index:100;top:100px;right:200px;width:300px;height:100px; color:#449daf; ' onmousedown='divBlock_event_mousedown()'><span onclick='closeDiv()' style='float:right;cursor:pointer;'>关闭</span></div>";
document.body.insertAdjacentHTML("afterBegin",str);
document.getElementById("div_Dialog").insertAdjacentHTML("beforeEnd",document.getElementById("div_a").innerHTML);
</script>