function insertAfter(ele,html){    var new_ele = document.createElement("div");    new_ele.innerHTML = html;    var parent = ele.parentNode || document.body;    parent.insertBefore(new_ele.firstChild, ele.nextSibling);}var d = document.getElementById("test");insertAfter(d,"
     
      dddddddd
     
")

 

 

     
      a    
      
       Item1
      
    
      
       Item2
      
    
      
       Item3
      
    
      
       Item4
      
b
     

 

var d = document.getElementById("test");d.childNodes;//...d.previousSibling;//nulld.nextSibling;//nulld.parentNode;//bodyd.firstChild;//ad.lastChild;//bd.lastChild.textContent;//bd.lastChild.previousSibling.innerHTML;//Item4d.childElementCount;//4d.lastElementChild;//
     
      Item4
     
d.childNodes.length;//9d.childNodes[0];//"a"d.childNodes[1];//
     
      Item1
     
d.childNodes[2];//""