如何复制百度文章

<div>
 
       <input type="button" value="复制" 
"var selectText = window.getSelection();var obj=document.getElementById('txt');
obj.innerHTML=selectText;obj.select();document.execCommand('Copy');">
 
<textarea id="txt" rows="6" cols="40"></textarea>
 
</div>

通过代码段获取