javascript - NotFoundError: DOM Exception 8 on insertBefore in event listener -

i have following code:

html:

<div id="tree">   <ul class="root">     <li class="add">+</li>   </ul> </div> 

javascript:

window.onload = () => {   let root = document.getelementsbyclassname("root")[0];   root.addeventlistener("click", (e) => {     if (e.target.classlist.contains("add")) addnode(e);     return false;   }, false);    function addnode(e) {     let item = document.createelement("li");     item.innerhtml = "new";     e.target.parentnode.insertbefore(e.target, item);   } }; 

when click li error notfounderror: dom exception 8: attempt made reference node in context not exist. on line insertbefore. i've checked devtools , seems normal node, have no idea why doesn't work.

the order of arguments incorrect. new node has passed first:

e.target.parentnode.insertbefore(item, e.target); 

see mdn documentation.