[jQuery] Selecting element where the href contains string

[gray8110]

I'm trying to add a class to a <li> where the href within it contains
a string.  I can apply the class to the anchor without a problem, but
I can't seem to select the parent. Is an anchor a child?

<li><a href="random.xls">Random Stuff</a></li>

In this case, since the href contains .xls, I'd like to be able to add
a class to it. I've tried a variety of things, most recently this, but
no luck:

$('li has(a[href$=".xls"])').addClass('excel');

any ideas?

Thanks