[inebriate]

you should use document.getElementsByTagName("select") rather than using product option id's since some products may have multiple options

that will return an array of all the elements that have the <select> tags

you would then loop through each array element's value and if it equals "noneselected" (replace with the value you used for the default none selected option, if it doesnt have a value, assign one) or you can compare with the index equaling 0

if the loop stumbles upon just 1 thats not selected, break the loop and throw an error message