Javascript show/hid div and change a css class based on which div is visible?

I have little piece of javascript to show/hide divs based on which link is clicked in a list. Its not very eligant, but it works fine. What I'd like to do is to assign an active state the a list item depending on which div is showing. Here is my JS and HTML:

var ids=new Array('section1','section2','section3','section4');

function switchid(id){  
    hideallids();
    showdiv(id);
}

function hideallids(){
    //loop through the array and hide each element by id
    for (var i=0;i<ids.length;i++){
        hidediv(ids[i]);
    }         
}

function hidediv(id) {
    //safe function to hide an element with a specified id
     开发者_如何学编程   document.getElementById(id).style.display = 'none';
}

function showdiv(id) {
    //safe function to show an element with a specified id        
        document.getElementById(id).style.display = 'block';
}

html:

<ul>
<li class="activeItem"><a href="javascript:switchid('section1');">One</a></li>
<li><a href="javascript:switchid('section2');">Two</a></li>
<li><a href="javascript:switchid('section3');">Three</a></li>
<li><a href="javascript:switchid('section4');">Four</a></li>
</ul>

<div id="section1" style="display:block;">1111111</div>
<div id="section2" style="display:none;">2222222</div>
<div id="section3" style="display:none;">3333333</div>
<div id="section4" style="display:none;">4444444</div>

When section 2 (or whichever) is clicked, I'd like the class "activeItem" to be removed from the li it is currently on and applied to the current li. Is this possible with javascript? I think it is, but I can't figure out how to implement it client side.

Thanks!

If you're able to use jQuery (or something similar) as it has this ability built in: http://docs.jquery.com/Attributes - addClass/removeClass

Change your anchors to use the onclick event instead of the href javascript code.

<a onclick="switchid('section1');return false;">One</a>

Then pass the argument this into your switchid function. this is a javascript keyword which in this scenario refers to the element (a).

<a onclick="switchid('section1', this);return false;">One</a>

Now to make the switchid function modify the list.

function switchid(id, el){  
    hideallids();
    showdiv(id);

    // rejiggered for text nodes
    var li = el.parentNode.parentNode.childNodes[0];
    while (li) {
        if (!li.tagName || li.tagName.toLowerCase() != "li")
            li = li.nextSibling; // skip the text node
        if (li) {
            li.className = "";
            li = li.nextSibling;
        }
    }

    el.parentNode.className = "activeItem";
}

Try it out: http://jsbin.com/esazu3/edit