[jQuery] Grabbing text inside an alt tag

Is there a way to grab the text from inside a alt tag? I have a site
that will have tons of span tags and I need to go through all of them
searching for the alt="" attribute then grab it.

I'm using some non-jQuery javascript, so I'm sure there is an easier
way to format this than what I currently have. Any thoughts on this
would be great.

----- html example:

<span>text here</span>
<span alt="Joe">text here</span>
<span alt="Jim">text here</span>
<span>text here</span>

----- Javascript.

// grab all spans on page.
var elem = window.opener.document.getElementsByTagName("span");

// make sure spans have alt attribute
for (var i = 0; i < elem.length; i++) {
if (!!$(elem[i]).attr("printElement")) {

???? Where do I go from here?
..... would like to do a document.write(span element
alt value);

}

}

Any thoughts on this would be great.