Unity and Website Javascript

On my website, I can pull the Username of the signed in user by executing a javascript in the console( In Chrome) by typing

javascript : document.getElementById("item-user").innerText)

The problem is, I need this information INSIDE the WebPlayer during runtime. Is is possible using Application.ExternalCall; or Application.ExternalEval? I dont understand because I hear that Unity cannot execute javascript commands.

Snippit of my Script Right now

if(GUILayout.Button("Get My UserName", titleStyle)){
Application.ExternalCall("document.getElementById('item-user').innerText");
}

Inside the HTML( for the .unity3d file) I added:

function GetUserName(){
     if(document.getElementById("fw-member-presence").firstChild.innerText != null){
         var unity = GetUnity();
         unity.SendMessage("WebPhone", "PickUp", document.getElementById("fw-member-presence").firstChild.innerText);
          }     
         }

In the console I did

javascript : GetUserName()

This found my function that I created and got the return value.
Use This manual to help you

NOTE: This works for a webs.com account ONLY