[jQuery] Getting Parent Element using "this"

[briandichiara]

I have a page where I need to get a parent forms action after firing
the onchange event on a select, like so:

<form action="something">
<select name="some_name" onchange="changeAction(this);">
<!-- some options -->
</select>
</form>

I can't figure out how to use "this" + a selector with jQuery,

I've tried

function changeAction(elm){
    var formAction = elm.$(":parent form").attr("action");
}

I really have no clue how to do effectively use "this" + a selector.