js 样式不更新

Question

I have a piece of code which is making me really crazy: I have a horizontal menu in my website, and on a mouseover event on one of the items a vertical submenu appears. I got this to work. The html looks something like this (don't mind the js for now, comments are also not in the real html):

<ul class="menu" onmouseout="menu('item',false)">  //the real html has some code to prevent nested elements to call the onmouseout event
    <li id="itemLI">
        <ul onmouseover="menu('item',true)">
            <li><img src=somesource width=somewidth /></li>
            <li class="drowdown item">submenuitem which is wider than the main menu item</li> //hidden until mouseover of the main item
        </ul>
    </li>
    //somemoreitems
</ul>

However, some submenu items are wider than the main menu items they belong to. Since the submenu items are variable, it's impossible to hard-code their width. Instead I try to get their width on mouseover, and then I want to change the width of the ul to the width of the longest item. The javascript code I use is this:

var orwidth = 0;
function menu(menuItem,show)
{
    //change menu width
    var item = menuItem + "LI";
    if (show)
    {
        //The important part which doesn't work
        var element = document.getElementById(item);
        var style = getComputedStyle(element,null);
        orwidth = style.width;
        element.style.width = "auto";
        style = getComputedStyle(element,null);
        alert(style.width);
    }
    else
    {
        document.getElementById(item).style.width = orwidth;
    }
    //show submenu
    if (show)
    {
        var visible ="visible";
    }
    else
    {
        var visible = "hidden";
    }
    var lis = document.getElementsByTagName("li");
    for (temp in lis)
    {
        if (lis[temp].className.indexOf("dropdown") != -1 && lis[temp].className.indexOf(menuItem) != -1)
        {
            lis[temp].style.visibility = visible;
        }
    }

}

as you can see, if the menu is shown the original width is saved, and a new width is applied. The alert function alerts the correct new width. However, for some reason the new width isn't shown on the page.

I just can't find out what I'm doing wrong. Can anyone help me?

edit: I didn't thought of the pure css solution. However, I still want to know why the page wasn't updated. Does anyone has the answer to that?

Answer 1

This seems like a lot of engineering to acheive something rather simple. Firstly, have you considered fixed widths for the drop-down results.

Next have you checked out the many many pure CSS examples out there, so you don't need to use JavaScript at all?

http://csswizardry.com/2011/02/creating-a-pure-css-dropdown-menu/