function insertAfter(newElement,targetElement){
    var parent=targetElement.parentNode;
    if(parent.lastChild==targetElement){
        parent.appendChild(newElement);
    }else{
        parent.insertBefore(newElement,targetElement.nextSibling);
    }
}

注：newElement=document.getElementById("id");

targetElement为刚创建的节点。例：

var para=document.createElement("p");

var para.setAttribute("id","desription");(等价于var testdiv=document.getElementById("description");testdiv.appendChild(para);)

var text=document.createTextNode("Hello world");

para.appendChila(text);

newElement=para;