Javascript & Combobox - Send the value of an item focused

I have a combobox with some values :

<select id="combo" name="my_combo" size="0" onchange="myFunction(this.getFocusedValue)"> 
    <option value="1">1 Me开发者_开发问答se</option>
    <option value="2">2 Mesi</option>
    <option value="3">3 Mesi</option>
    <option value="4">4 Mesi</option>
</select>

I want to translate that this.getFocusedValue on a real JavaScript code :)

How can I do this? Would be nice if this works on all browser (else i can use Jquery).

Thanks

SOLUTION

<select id="combo" name="my_combo" size="0" onchange="changeArticle(this.options[this.selectedIndex].value)">

this.selectedIndex;

Edit:

index = this.selectedIndex;
return this.options[index].value;