js动态生成浮动div

要求点击输入框，弹出浮动div，div覆盖在输入框上方，可进行修改操作。
效果图：

function editBehaviorDiv(obj,id,value){
	var div=document.getElementById("editBehaviorDiv");
	if(div!=null)
		document.body.removeChild(div);
	saveRiskInfo();
	div = document.createElement("div"); 
	div.id="editBehaviorDiv";
	div.style.position='absolute';
	var op=getoffset(obj);
	div.style.top=op[0];
	div.style.left=op[1];
	div.style.zIndex =100;
	div.style.backgroundColor='#ecf1f6';
	div.style.border="1px solid #666";
	//div.className="td1";
	div.innerHTML="<textarea name='behaviorValue' cols='50' rows='8'>"+value+
	"</textarea><br/><input type='button' value='修改' onclick=\"saveBehaviorname(this.parentNode,'"+id+"')\" />"+
	"<input type='button' value='取消' onclick='document.body.removeChild(this.parentNode);'/>";
	document.body.appendChild(div);
	document.all.behaviorValue.focus();
}
function saveBehaviorname(obj,id){
	var riskbehavior=document.all.behaviorValue.value;
	LawriskUtil.saveBehaviorName(id,riskbehavior,function(data){
		//obj1.value=riskbehavior;
		getNewRiskList();
		document.body.removeChild(obj);
	});
}
function getoffset(e) 
{ 
var t=e.offsetTop; 
var l=e.offsetLeft; 
while(e=e.offsetParent) 
{ 
   t+=e.offsetTop; 
   l+=e.offsetLeft; 
} 
var rec = new Array(1); 
rec[0] = t; 
rec[1] = l; 
return rec 
} 

测试
<input type='text' size='20' name='riskbehavior'value='行为' 
	onclick=editBehaviorDiv(this,'1','行为') >