文本框被隐藏后却不可以编辑了解决办法

文本框被隐藏后却不可以编辑了
如题，谢谢

[解决办法]
document.getElementById('box').innerHTML=" <input id='sipuri' name='sipuri' style='width:200px;height:21px'/>"+ " <span style='width:18px;border:0px;'>" 
+ " <select name='sip_uri' style='margin-left:-200px;width:218px;\' onChange=\"SeltxtToText()\";>" 
+ " <option>&nbsp; </option> <option value='1'>1 </option><option value='2'>2 </option><option value='3'>3 </option>"+" </select>" +" </span>";
function SeltxtToText(){
document.getElementById("sipuri").value=document.getElementById("sip_uri").value;
}