element.firstChild is returning '<TextNode ...' instead of an Object in FF

Question

I wrote a tab system using some very basic Javascript and it runs like a champ in IE 8 but, in FireFox 3 I am coming up short. The pertitent HTML is as follows:

            <div id="tabs">
                <ul class="tabs">
                    <li class="current"><a><span>News</span></a></li>
                    <li><a><span>Videos</span></a></li>
                    <li><a><span>Photos</span></a></li>
                    <li><a><span>Twitter</span></a></li>
                </ul>
            </div>

Then, on page load, I get dropped into this method:

function processTabs(TabContainer, PageContainer, Index) {
var tabContainer = document.getElementById(TabContainer);
var tabs = tabContainer.firstChild;

var tab = tabs.firstChild;
var i = 0;
.... more code }

The rest of the code does not matter at this point because it never gets called. tabContainer is set properly to reference the div with the ID tabs. Now, in Internet Explorer when I call tabContainer.firstChild the variable 'tabs' is referencing my UL and then the call var tab = tabs.firstChild; references my first LI. The problem is that when I call tabContainer.firstChild Venkman is telling me it is returning . So firefox is reading my newlines as actual children inside the div's! My UL is actually the second child in the childNodes collection!

Is there any way to fix this?

Thanks!

Answer 1

You can use node.firstElementChild to ignore leading text, or use a library like jQuery which takes care of this.

Answer 2

You should skip the TextNodes, a simple function can help you:

function getFirstChild(el){
  var firstChild = el.firstChild;
  while(firstChild != null && firstChild.nodeType == 3){ // skip TextNodes
    firstChild = firstChild.nextSibling;
  }
  return firstChild;
}

Usage:

var tabContainer = document.getElementById(TabContainer);
var tabs = getFirstChild(tabContainer);

Answer 3

I would recommend anyone trying to work with the DOM in javascript to use a library like jquery. It will make your life much easier.

You could then rewrite the JS function as fallows:

function processTabs(TabContainer, PageContainer, Index) {
    var tabContainer = document.getElementById(TabContainer);

    // jquery used to find all the <li> elements
    var tabs = $(tabContainer).filter('li');

    // use the jquery get( index ) function to retrieve the first tab
    var tab = tabs.get(0);
    var i = 0;
    .... more code
}

Answer 4

With a an eye also on efficency, this fucntion returns firstChild element node of el

function firstChildElement(el)
{
   do el = el.firstChild;
   while( el && (el.nodeType != 1) );   
   return el;
}