JavaScript loop returning undefined

Question

I'm trying to code a function that will loop through the child nodes of my “main” div element, and outputting element tag names out onto an hmtl page and every time I try to compile my code i end up getting undefined. Can anyone shed some light as to why?

Could it be because Console.log returns undefined? But if it does shouldn't I still be receiving some sort of output from my for loop?

function looper() {         //function that will loop through the child nodes of main

    var nodes = document.getElementById('main').childNodes;

    for(i=0; i<nodes.length; i++) {
        console.log(nodes[i]);
    }
}

HTML

 <div id ="main">

 <h1> Jimms web site </h1>

 <nav>
   <a href="index.html">Home page</a> |
   <a href="about.html">About me</a> |
   <a href="contact.html">Contact me</a> 
 </nav> 

     <p> This is a list: </p>
     <div> 
     <ol id = "list">
      <li><a href="mega">hi</a> - </li>
      <li><a href="mario">mario</a> - </li>
      <li><a href="luigi">luigi</a> - </li>
      <li><a href="mash">mash</a> - </li>
      <li><a href="mash">mash</a> - </li></ol>
      </div>
      <p> Thats it </p>



 </div>

  looper();

Answer 1

Your are probably call the javascript before DOM is ready. Put the call to the function just before ending body tag.

Live Demo

function looper() {         //function that will loop through the child nodes of main

    var nodes = document.getElementById('main').childNodes;

    for(i=0; i<nodes.length; i++) {
        document.write(nodes[i]);
    }
}

Call the looper just before body tag to ensure the availability of DOM elements.

    <script type="text/javascript" >
        looper();
    </script> 

</body>