How to dynamically create and remove divs in js_javascript skills

//创建div
function createDiv(){
 if(document.getElementByIdx_x("newD")!=null)
  document.body.removeChild(document.getElementByIdx_x("newD"));
 var Div = document.create_rElement("div");//创建div
 Div.setAttribute("id", "newD");
 Div.style.position = "absolute";
 Div.style.height = "160px";
 Div.style.width = "400px";
 Div.style.border = "1px solid grey";
 Div.style.background = "white";
 Div.style.paddingTop = "40px";
 Div.style.zIndex = "100";
 Div.style.left = 100 +"px";//注意Firefox下必须加"px"
 Div.style.top = 100 +"px";
 Div.style.textAlign = "center";
 Div.style.fontSize = "18px";
 var str = "<div id=\"divClose\" onclick=\"removeDiv()\" style=\"width:16px;height:16px;float:right;margin-top:-40px;background:url(images/divClose.gif);\"><\/div>";
 Div.innerHTML = str + title;
 document.body.appendChild(newD);
}
//移除创建的div
function removeDiv(){
 document.body.removeChild(document.getElementByIdx_x_x("newD"));
}