Using To Check Drop-down Lists?

I've tried w3schools, tizag, and google, but haven't found exactly what I need. I need some way of easily figuring out which option in a drop down menu is checked, through the use of javascript, like how you can use document.formname.elementname[i].checked to find out which checkbox/radio button is checked. Anything that would return something that allows me to figure out which option has been chosen. I will need to have a function with 3 if statements, one for each option.